{"authors":[{"name":"Martin Stühmer","url":"https://daily-devops.net/authors/martin/"},{"name":"Jendrik Brack","url":"https://daily-devops.net/authors/jendrik/"}],"description":"Recent content in ASP.NET Core: Building Modern Web Applications on Daily DevOps \u0026 .NET","favicon":"https://daily-devops.net/images/logo_hu_6465d873dfa490cf.png","feed_url":"https://daily-devops.net/tags/aspnet-core/feed.json","home_page_url":"https://daily-devops.net/tags/aspnet-core/","icon":"https://daily-devops.net/images/logo_hu_5926de77762241ba.png","items":[{"authors":[{"name":"Martin Stühmer","url":"https://daily-devops.net/authors/martin/"}],"content_html":"\u003cp\u003eException stack traces in production API responses. Database connection strings leaked through error messages. Internal file paths revealed to unauthenticated clients. These aren\u0026rsquo;t hypothetical scenarios. They show up in nearly every security assessment I conduct on .NET applications, and they\u0026rsquo;re textbook ISO/IEC 27001 violations.\u003c/p\u003e\n\u003cp\u003eWhat makes this frustrating? Error handling sits in a blind spot for most teams. Developers invest real effort catching exceptions, returning \u0026ldquo;helpful\u0026rdquo; messages, configuring logging frameworks, building dashboards. All with good intentions. Yet that same exception handling strategy often violates security controls mandated by ISO 27001. The irony: being \u0026ldquo;helpful\u0026rdquo; to API consumers means being equally helpful to attackers.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"the-iso-27001-perspective-on-error-messages\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#the-iso-27001-perspective-on-error-messages\" title=\"The ISO 27001 Perspective on Error Messages\"\u003eThe ISO 27001 Perspective on Error Messages\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eYou won\u0026rsquo;t find a control titled \u0026ldquo;Don\u0026rsquo;t leak stack traces\u0026rdquo; in ISO/IEC 27001. The requirements are subtler and more encompassing. Three controls directly govern how your .NET applications should handle errors:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eControl A.12.4.1 (Event Logging)\u003c/strong\u003e requires logging security events for detection and investigation. Exception details belong in logs accessible to your operations team, not in HTTP responses returned to potentially malicious clients. This distinction matters more than most teams realize: logs are protected internal records, while HTTP responses cross trust boundaries.\u003c/p\u003e\n\n\n\n\n\u003ch3 id=\"environment-separation-is-non-negotiable\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#environment-separation-is-non-negotiable\" title=\"Environment Separation Is Non-Negotiable\"\u003eEnvironment Separation Is Non-Negotiable\u003c/a\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eControl A.14.2.6 (Secure Development Environment)\u003c/strong\u003e mandates separating development, testing, and production environments with different security configurations. That detailed stack trace in your development environment? Perfectly fine. The same behavior in production? Compliance violation. Environment-specific error handling isn\u0026rsquo;t a nice-to-have. It\u0026rsquo;s a requirement.\u003c/p\u003e\n\n\n\n\n\u003ch3 id=\"stack-traces-as-intellectual-property-leaks\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#stack-traces-as-intellectual-property-leaks\" title=\"Stack Traces As Intellectual Property Leaks\"\u003eStack Traces As Intellectual Property Leaks\u003c/a\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eControl A.18.1.2 (Intellectual Property Rights)\u003c/strong\u003e addresses protection of organizational knowledge. Source code file paths, internal architecture details, and technology stack versions revealed through exception messages constitute intellectual property disclosure. An attacker learning that \u003ccode\u003eOrderProcessingService.cs\u003c/code\u003e line 347 threw a \u003ccode\u003eNullReferenceException\u003c/code\u003e now has architectural intelligence that aids further attacks.\u003c/p\u003e\n\u003cp\u003eThese controls don\u0026rsquo;t prohibit exceptions. They require deliberate separation between what gets logged internally and what gets returned externally. Your ASP.NET Core implementation determines compliance.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"fatal-pattern-the-helpful-exception\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#fatal-pattern-the-helpful-exception\" title=\"Fatal Pattern: The Helpful Exception\"\u003eFatal Pattern: The Helpful Exception\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eThis pattern appears in countless production APIs. It looks like proper error handling. It feels like you\u0026rsquo;re being helpful. It violates all three ISO 27001 controls:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-csharp\" data-lang=\"csharp\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"c1\"\u003e// Fatal: Detailed exception information returned directly to clients\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e[HttpPost]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kd\"\u003easync\u003c/span\u003e \u003cspan class=\"n\"\u003eTask\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eActionResult\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eOrderResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026gt;\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003eCreateOrder\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eCreateOrderRequest\u003c/span\u003e \u003cspan class=\"n\"\u003erequest\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003etry\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"kt\"\u003evar\u003c/span\u003e \u003cspan class=\"n\"\u003eorder\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"k\"\u003eawait\u003c/span\u003e \u003cspan class=\"n\"\u003e_orderService\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eCreateOrderAsync\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003erequest\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eOk\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eorder\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003ecatch\u003c/span\u003e \u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eException\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"c1\"\u003e// Fatal: Returning full exception details to client\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eBadRequest\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"k\"\u003enew\u003c/span\u003e \n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"p\"\u003e{\u003c/span\u003e \n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003eerror\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eMessage\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003estackTrace\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eStackTrace\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003einnerException\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eInnerException\u003c/span\u003e\u003cspan class=\"p\"\u003e?.\u003c/span\u003e\u003cspan class=\"n\"\u003eMessage\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"p\"\u003e});\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eWhen this code encounters a database connectivity issue, the HTTP response includes:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-json\" data-lang=\"json\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;error\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s2\"\u003e\u0026#34;A network-related error occurred establishing a connection to SQL Server...\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;stackTrace\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s2\"\u003e\u0026#34;at OrderService.CreateOrderAsync() in C:\\\\Projects\\\\ECommerce\\\\Services\\\\OrderService.cs:line 127\u0026#34;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eThis response violates all three ISO controls. No structured logging occurred (A.12.4.1). Production behaves identically to development (A.14.2.6). Internal file paths and technology stack details are fully exposed (A.18.1.2).\u003c/p\u003e\n\n\n\n\n\u003ch3 id=\"what-an-attacker-learns-from-this-response\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#what-an-attacker-learns-from-this-response\" title=\"What An Attacker Learns From This Response\"\u003eWhat An Attacker Learns From This Response\u003c/a\u003e\u003c/h3\u003e\n\u003cp\u003eAn attacker now knows the application uses SQL Server, the internal project structure, exact file paths, and line numbers. Equally problematic: no correlation ID was generated, no security event was logged, and no alert triggered when hundreds of these errors originate from the same source IP.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"fatal-pattern-the-model-validation-leak\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#fatal-pattern-the-model-validation-leak\" title=\"Fatal Pattern: The Model Validation Leak\"\u003eFatal Pattern: The Model Validation Leak\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eModel validation errors fly under the radar more often than exception handling. They seem harmless, just input validation feedback. But they can expose your internal data model:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-csharp\" data-lang=\"csharp\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"c1\"\u003e// Fatal: Detailed validation errors exposing schema structure\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"k\"\u003eclass\u003c/span\u003e \u003cspan class=\"nc\"\u003eCreateOrderRequest\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    [Required]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    [CreditCard]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kt\"\u003estring\u003c/span\u003e \u003cspan class=\"n\"\u003ePaymentToken\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eget\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"k\"\u003eset\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    \n\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    [Required]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kt\"\u003estring\u003c/span\u003e \u003cspan class=\"n\"\u003eInternalProcessingCode\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eget\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"k\"\u003eset\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e  \u003cspan class=\"c1\"\u003e// Internal field!\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e[HttpPost]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"n\"\u003eActionResult\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eOrderResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003eCreateOrder\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eCreateOrderRequest\u003c/span\u003e \u003cspan class=\"n\"\u003erequest\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003eif\u003c/span\u003e \u003cspan class=\"p\"\u003e(!\u003c/span\u003e\u003cspan class=\"n\"\u003eModelState\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eIsValid\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eBadRequest\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eModelState\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e  \u003cspan class=\"c1\"\u003e// Fatal: Exposes all fields\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eOk\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"k\"\u003enew\u003c/span\u003e \u003cspan class=\"n\"\u003eOrderResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e());\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eWhen a client submits an invalid request, ASP.NET Core\u0026rsquo;s default behavior returns:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-json\" data-lang=\"json\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;errors\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"nt\"\u003e\u0026#34;PaymentToken\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"p\"\u003e[\u003c/span\u003e\u003cspan class=\"s2\"\u003e\u0026#34;The PaymentToken field is not a valid credit card number.\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e],\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"nt\"\u003e\u0026#34;InternalProcessingCode\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"p\"\u003e[\u003c/span\u003e\u003cspan class=\"s2\"\u003e\u0026#34;The InternalProcessingCode field is required.\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eThe client now knows that an \u003ccode\u003eInternalProcessingCode\u003c/code\u003e field exists, even though it wasn\u0026rsquo;t documented in public API specs. This constitutes schema disclosure, revealing internal data model details beyond the public API contract. ISO 27001 Control A.18.1.2 applies here as much as to source code paths.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"correct-pattern-exception-middleware-with-environment-awareness\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#correct-pattern-exception-middleware-with-environment-awareness\" title=\"Correct Pattern: Exception Middleware with Environment Awareness\"\u003eCorrect Pattern: Exception Middleware with Environment Awareness\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eThe fix centralizes exception management in middleware. Log everything internally, return nothing sensitive externally, and adapt behavior based on environment:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-csharp\" data-lang=\"csharp\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"k\"\u003eclass\u003c/span\u003e \u003cspan class=\"nc\"\u003eSecureExceptionMiddleware\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eRequestDelegate\u003c/span\u003e \u003cspan class=\"n\"\u003enext\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"n\"\u003eILogger\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eSecureExceptionMiddleware\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003elogger\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"n\"\u003eIHostEnvironment\u003c/span\u003e \u003cspan class=\"n\"\u003eenvironment\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kd\"\u003easync\u003c/span\u003e \u003cspan class=\"n\"\u003eTask\u003c/span\u003e \u003cspan class=\"n\"\u003eInvokeAsync\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eHttpContext\u003c/span\u003e \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003etry\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eawait\u003c/span\u003e \u003cspan class=\"n\"\u003enext\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003ecatch\u003c/span\u003e \u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eException\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eawait\u003c/span\u003e \u003cspan class=\"n\"\u003eHandleExceptionAsync\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"n\"\u003eex\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003eprivate\u003c/span\u003e \u003cspan class=\"kd\"\u003easync\u003c/span\u003e \u003cspan class=\"n\"\u003eTask\u003c/span\u003e \u003cspan class=\"n\"\u003eHandleExceptionAsync\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eHttpContext\u003c/span\u003e \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"n\"\u003eException\u003c/span\u003e \u003cspan class=\"n\"\u003eexception\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"kt\"\u003evar\u003c/span\u003e \u003cspan class=\"n\"\u003ecorrelationId\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eActivity\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eCurrent\u003c/span\u003e\u003cspan class=\"p\"\u003e?.\u003c/span\u003e\u003cspan class=\"n\"\u003eId\u003c/span\u003e \u003cspan class=\"p\"\u003e??\u003c/span\u003e \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eTraceIdentifier\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"c1\"\u003e// Log full details internally\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"n\"\u003elogger\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eLogError\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eexception\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"s\"\u003e\u0026#34;CorrelationId: {CorrelationId}, Path: {Path}\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003ecorrelationId\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eRequest\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003ePath\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eContentType\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"s\"\u003e\u0026#34;application/problem+json\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eStatusCode\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"m\"\u003e500\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"kt\"\u003evar\u003c/span\u003e \u003cspan class=\"n\"\u003eproblemDetails\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"k\"\u003enew\u003c/span\u003e \u003cspan class=\"n\"\u003eProblemDetails\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003eType\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"s\"\u003e\u0026#34;https://httpstatuses.com/500\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003eTitle\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"s\"\u003e\u0026#34;Internal Server Error\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003eStatus\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"m\"\u003e500\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"n\"\u003eExtensions\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"p\"\u003e[\u003c/span\u003e\u003cspan class=\"s\"\u003e\u0026#34;correlationId\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e]\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003ecorrelationId\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"p\"\u003e};\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"c1\"\u003e// Environment-aware detail level\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"n\"\u003eproblemDetails\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eDetail\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eenvironment\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eIsDevelopment\u003c/span\u003e\u003cspan class=\"p\"\u003e()\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"p\"\u003e?\u003c/span\u003e \u003cspan class=\"n\"\u003eexception\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eMessage\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s\"\u003e$\u0026#34;Reference correlation ID {correlationId} when contacting support.\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003eawait\u003c/span\u003e \u003cspan class=\"n\"\u003econtext\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eWriteAsJsonAsync\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eproblemDetails\u003c/span\u003e\u003cspan class=\"p\"\u003e);\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\n\n\n\n\u003ch3 id=\"wiring-the-middleware-into-the-pipeline\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#wiring-the-middleware-into-the-pipeline\" title=\"Wiring The Middleware Into The Pipeline\"\u003eWiring The Middleware Into The Pipeline\u003c/a\u003e\u003c/h3\u003e\n\u003cp\u003eRegister this middleware early in \u003ccode\u003eProgram.cs\u003c/code\u003e:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-csharp\" data-lang=\"csharp\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"n\"\u003eapp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eUseMiddleware\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eSecureExceptionMiddleware\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026gt;();\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"n\"\u003eapp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eUseAuthentication\u003c/span\u003e\u003cspan class=\"p\"\u003e();\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"n\"\u003eapp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eUseAuthorization\u003c/span\u003e\u003cspan class=\"p\"\u003e();\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"n\"\u003eapp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eMapControllers\u003c/span\u003e\u003cspan class=\"p\"\u003e();\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eNow the production response becomes generic but actionable:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-json\" data-lang=\"json\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;title\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s2\"\u003e\u0026#34;Internal Server Error\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;status\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"mi\"\u003e500\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;detail\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s2\"\u003e\u0026#34;Reference correlation ID 00-4bf92f3577b34da6a3ce929d0e0e4736-00 when contacting support.\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;correlationId\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"s2\"\u003e\u0026#34;00-4bf92f3577b34da6a3ce929d0e0e4736-00\u0026#34;\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eThe full exception with stack trace goes to Application Insights, linked by that same correlation ID. Operations teams get everything they need for investigation. Clients get nothing useful for exploitation.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"correct-pattern-secure-model-validation\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#correct-pattern-secure-model-validation\" title=\"Correct Pattern: Secure Model Validation\"\u003eCorrect Pattern: Secure Model Validation\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eModel validation needs the same discipline. Filter internal fields before they reach the response:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-csharp\" data-lang=\"csharp\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"k\"\u003eclass\u003c/span\u003e \u003cspan class=\"nc\"\u003eCreateOrderRequest\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    [Required(ErrorMessage = \u0026#34;Payment information is required.\u0026#34;)]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kt\"\u003estring\u003c/span\u003e \u003cspan class=\"n\"\u003ePaymentToken\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eget\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"k\"\u003eset\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    \n\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e    [JsonIgnore]\u003c/span\u003e  \u003cspan class=\"c1\"\u003e// Internal field: never exposed\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"kt\"\u003estring\u003c/span\u003e \u003cspan class=\"n\"\u003eInternalProcessingCode\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e \u003cspan class=\"k\"\u003eget\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"k\"\u003eset\u003c/span\u003e\u003cspan class=\"p\"\u003e;\u003c/span\u003e \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"na\"\u003e[HttpPost]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"kd\"\u003epublic\u003c/span\u003e \u003cspan class=\"n\"\u003eActionResult\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026lt;\u003c/span\u003e\u003cspan class=\"n\"\u003eOrderResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003eCreateOrder\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003eCreateOrderRequest\u003c/span\u003e \u003cspan class=\"n\"\u003erequest\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003eif\u003c/span\u003e \u003cspan class=\"p\"\u003e(!\u003c/span\u003e\u003cspan class=\"n\"\u003eModelState\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eIsValid\u003c/span\u003e\u003cspan class=\"p\"\u003e)\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"c1\"\u003e// Filter out internal fields before returning\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"kt\"\u003evar\u003c/span\u003e \u003cspan class=\"n\"\u003epublicErrors\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u003c/span\u003e \u003cspan class=\"n\"\u003eModelState\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eWhere\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003ekvp\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u0026gt;\u003c/span\u003e \u003cspan class=\"p\"\u003e!\u003c/span\u003e\u003cspan class=\"n\"\u003ekvp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eKey\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eContains\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"s\"\u003e\u0026#34;Internal\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e))\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e            \u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eToDictionary\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003ekvp\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003ekvp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eKey\u003c/span\u003e\u003cspan class=\"p\"\u003e,\u003c/span\u003e \n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e                \u003cspan class=\"n\"\u003ekvp\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003ekvp\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eValue\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eErrors\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eSelect\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003ee\u003c/span\u003e \u003cspan class=\"p\"\u003e=\u0026gt;\u003c/span\u003e \u003cspan class=\"n\"\u003ee\u003c/span\u003e\u003cspan class=\"p\"\u003e.\u003c/span\u003e\u003cspan class=\"n\"\u003eErrorMessage\u003c/span\u003e\u003cspan class=\"p\"\u003e).\u003c/span\u003e\u003cspan class=\"n\"\u003eToArray\u003c/span\u003e\u003cspan class=\"p\"\u003e());\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e        \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eBadRequest\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"k\"\u003enew\u003c/span\u003e \u003cspan class=\"n\"\u003eValidationProblemDetails\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"n\"\u003epublicErrors\u003c/span\u003e\u003cspan class=\"p\"\u003e));\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"k\"\u003ereturn\u003c/span\u003e \u003cspan class=\"n\"\u003eOk\u003c/span\u003e\u003cspan class=\"p\"\u003e(\u003c/span\u003e\u003cspan class=\"k\"\u003enew\u003c/span\u003e \u003cspan class=\"n\"\u003eOrderResponse\u003c/span\u003e\u003cspan class=\"p\"\u003e());\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eThe client now receives only sanitized validation errors:\u003c/p\u003e\n\u003cdiv class=\"highlight\"\u003e\u003cpre tabindex=\"0\" class=\"chroma\"\u003e\u003ccode class=\"language-json\" data-lang=\"json\"\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"nt\"\u003e\u0026#34;errors\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"p\"\u003e{\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e    \u003cspan class=\"nt\"\u003e\u0026#34;PaymentToken\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e:\u003c/span\u003e \u003cspan class=\"p\"\u003e[\u003c/span\u003e\u003cspan class=\"s2\"\u003e\u0026#34;Payment information is required.\u0026#34;\u003c/span\u003e\u003cspan class=\"p\"\u003e]\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e  \u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"line\"\u003e\u003cspan class=\"cl\"\u003e\u003cspan class=\"p\"\u003e}\u003c/span\u003e\n\u003c/span\u003e\u003c/span\u003e\u003c/code\u003e\u003c/pre\u003e\u003c/div\u003e\u003cp\u003eThe \u003ccode\u003eInternalProcessingCode\u003c/code\u003e field never appears in the response. Full validation failure details exist only in logs.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"health-checks-error-rates-as-security-indicators\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#health-checks-error-rates-as-security-indicators\" title=\"Health Checks: Error Rates as Security Indicators\"\u003eHealth Checks: Error Rates as Security Indicators\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eISO 27001 Control A.12.4.1 requires monitoring security events. Here\u0026rsquo;s what many teams miss: unusual error rates often signal active attacks. Enumeration attempts, credential stuffing, SQL injection probes, they all generate elevated error counts before any successful breach.\u003c/p\u003e\n\u003cp\u003eImplement an \u003ccode\u003eIHealthCheck\u003c/code\u003e that tracks errors per minute and returns \u003ccode\u003eHealthCheckResult.Degraded\u003c/code\u003e when rates exceed thresholds. Wire this into your exception middleware so every handled exception increments the counter. When error rates spike, the health check triggers alerts through Kubernetes readiness probes, Azure App Service monitoring, or your orchestration platform.\u003c/p\u003e\n\u003cp\u003eThe implementation is straightforward: record errors in middleware, expose metrics through health endpoints, let your infrastructure respond to anomalies. The value? You\u0026rsquo;re detecting potential attacks through a mechanism that already exists in most production deployments.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"correlation-ids-connecting-responses-to-logs\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#correlation-ids-connecting-responses-to-logs\" title=\"Correlation IDs: Connecting Responses to Logs\"\u003eCorrelation IDs: Connecting Responses to Logs\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eThe correlation ID pattern appears throughout these examples for a reason. It solves the operational problem that secure error handling creates: how do support teams investigate a production error when the client received only a generic message?\u003c/p\u003e\n\u003cp\u003eASP.NET Core\u0026rsquo;s \u003ccode\u003eActivity.Current?.Id\u003c/code\u003e provides distributed tracing identifiers compatible with W3C Trace Context standards. When using Application Insights, these correlation IDs automatically link HTTP requests, exception logs, database queries, downstream service calls, and performance telemetry into a single trace.\u003c/p\u003e\n\u003cp\u003eA client reporting \u0026ldquo;Error with correlation ID 00-4bf92f3577b34da6a3ce929d0e0e4736-00\u0026rdquo; gives your operations team the complete picture in Application Insights. Full stack trace, request details, downstream failures, everything. No information disclosure required in the original error response.\u003c/p\u003e\n\u003cp\u003eThis satisfies ISO 27001\u0026rsquo;s dual requirement: comprehensive logging for incident investigation (A.12.4.1) without exposing internal details to potentially malicious clients (A.18.1.2).\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"the-compliance-reality\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#the-compliance-reality\" title=\"The Compliance Reality\"\u003eThe Compliance Reality\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eISO 27001 certification audits examine error handling more closely than most teams expect. Auditors request sample API error responses and compare them against logged events. They verify environment-specific configurations exist and function correctly. They check that model validation errors don\u0026rsquo;t leak internal schema details.\u003c/p\u003e\n\u003cp\u003eThese aren\u0026rsquo;t theoretical controls. I\u0026rsquo;ve participated in audits where error handling implementations blocked certification until remediated. The fix required implementing exactly the patterns shown here: exception middleware with environment awareness, Problem Details responses, correlation IDs, and separation between logged events and client responses.\u003c/p\u003e\n\u003cp\u003eThe technical implementation is straightforward. The organizational challenge? Changing the mindset that \u0026ldquo;helpful error messages\u0026rdquo; improve developer experience. Detailed error messages in production don\u0026rsquo;t help legitimate users, they can\u0026rsquo;t act on \u0026ldquo;NullReferenceException at line 347\u0026rdquo; anyway. They assist attackers during reconnaissance and exploitation.\u003c/p\u003e\n\n\n\n\n\u003ch2 id=\"the-path-forward\"\u003e\u003ca href=\"/posts/error-handling-security-information-disclosure/#the-path-forward\" title=\"The Path Forward\"\u003eThe Path Forward\u003c/a\u003e\u003c/h2\u003e\n\u003cp\u003eSecure error handling in .NET applications comes down to six patterns:\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003e\u003cstrong\u003eException middleware\u003c/strong\u003e that intercepts all unhandled exceptions before they reach clients\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEnvironment-aware responses\u003c/strong\u003e providing detail in Development, generic messages in Production\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eProblem Details (RFC 7807)\u003c/strong\u003e as the standard error response format\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eCorrelation IDs\u003c/strong\u003e linking client responses to comprehensive internal logs\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eSelective model validation\u003c/strong\u003e exposing only public API contract violations\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eHealth monitoring\u003c/strong\u003e detecting elevated error rates as potential security events\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eThese patterns satisfy ISO 27001 Controls A.12.4.1 (Event Logging), A.14.2.6 (Secure Development Environment), and A.18.1.2 (Intellectual Property Rights). More importantly, they implement defense in depth by ensuring that routine error handling doesn\u0026rsquo;t become an information disclosure vulnerability.\u003c/p\u003e\n\u003cp\u003eThe next time your API throws an exception, ask one question: who benefits from this error message? If the answer is \u0026ldquo;potential attackers,\u0026rdquo; your error handling violates ISO 27001 requirements and creates security risk. If the answer is \u0026ldquo;operations teams investigating via correlation IDs in logs,\u0026rdquo; you\u0026rsquo;ve implemented the control correctly.\u003c/p\u003e\n","date_modified":"2026-05-26T10:22:03+02:00","date_published":"2026-03-12T17:00:00+01:00","id":"https://daily-devops.net/posts/error-handling-security-information-disclosure/","language":"en","summary":"That helpful stack trace in your API response is a roadmap for attackers. Learn secure error handling that logs everything but reveals nothing.","tags":["iso-standards","security","dotnet","aspnet-core"],"title":"Your Stack Traces Are Love Letters to Attackers","url":"https://daily-devops.net/posts/error-handling-security-information-disclosure/"}],"language":"en","title":"ASP.NET Core: Building Modern Web Applications on Daily DevOps \u0026 .NET","version":"https://jsonfeed.org/version/1.1"}