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michaelnebelmichaelnebel
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Merge pull request #15212 from michaelnebel/csharp/stringreplace
C#: Fix Log forging false positive.
2 parents 7c6d30b + 0c78ccc commit 682aef9

4 files changed

Lines changed: 16 additions & 10 deletions

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‎csharp/ql/lib/semmle/code/csharp/frameworks/System.qll‎

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Original file line numberDiff line numberDiff line change
@@ -346,11 +346,11 @@ class SystemStringClass extends StringType {
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result.hasName("==")
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}
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/** Gets the `Replace(string/char, string/char)` method. */
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/** Gets the `Replace(...)` method. */
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Method getReplaceMethod() {
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result.getDeclaringType() = this and
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result.hasName("Replace") and
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result.getNumberOfParameters() = 2 and
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result.getNumberOfParameters() in [2 .. 4] and
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result.getReturnType() instanceof StringType
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}
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‎csharp/ql/src/change-notes/2024-01-03-logforging-false-positive.md‎

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---
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category: minorAnalysis
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---
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* Fixed a Log forging false positive when using `String.Replace` to sanitize the input.

‎csharp/ql/test/query-tests/Security Features/CWE-117/LogForging.cs‎

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@@ -21,6 +21,8 @@ public void ProcessRequest(HttpContext ctx)
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logger.Warn(username + " logged in");
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// GOOD: New-lines removed
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logger.Warn(username.Replace(Environment.NewLine, "") + " logged in");
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// GOOD: New-lines removed
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logger.Warn(username.Replace(Environment.NewLine, "", StringComparison.InvariantCultureIgnoreCase) + " logged in");
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// GOOD: Html encoded
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logger.Warn(WebUtility.HtmlEncode(username) + " logged in");
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// BAD: Logged as-is to TraceSource

‎csharp/ql/test/query-tests/Security Features/CWE-117/LogForging.expected‎

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@@ -1,23 +1,23 @@
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edges
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:18:27:18:61 | access to indexer : String |
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:21:21:21:43 | ... + ... |
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:27:50:27:72 | ... + ... |
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:31:26:31:33 | access to local variable username |
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:29:50:29:72 | ... + ... |
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:33:26:33:33 | access to local variable username |
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| LogForging.cs:18:27:18:61 | access to indexer : String | LogForging.cs:21:21:21:43 | ... + ... |
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| LogForging.cs:18:27:18:61 | access to indexer : String | LogForging.cs:27:50:27:72 | ... + ... |
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| LogForging.cs:18:27:18:61 | access to indexer : String | LogForging.cs:31:26:31:33 | access to local variable username |
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| LogForging.cs:18:27:18:61 | access to indexer : String | LogForging.cs:29:50:29:72 | ... + ... |
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| LogForging.cs:18:27:18:61 | access to indexer : String | LogForging.cs:33:26:33:33 | access to local variable username |
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| LogForgingAsp.cs:8:32:8:39 | username : String | LogForgingAsp.cs:12:21:12:43 | ... + ... |
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nodes
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| LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | semmle.label | access to property QueryString : NameValueCollection |
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| LogForging.cs:18:27:18:61 | access to indexer : String | semmle.label | access to indexer : String |
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| LogForging.cs:21:21:21:43 | ... + ... | semmle.label | ... + ... |
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| LogForging.cs:27:50:27:72 | ... + ... | semmle.label | ... + ... |
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| LogForging.cs:31:26:31:33 | access to local variable username | semmle.label | access to local variable username |
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| LogForging.cs:29:50:29:72 | ... + ... | semmle.label | ... + ... |
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| LogForging.cs:33:26:33:33 | access to local variable username | semmle.label | access to local variable username |
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| LogForgingAsp.cs:8:32:8:39 | username : String | semmle.label | username : String |
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| LogForgingAsp.cs:12:21:12:43 | ... + ... | semmle.label | ... + ... |
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subpaths
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#select
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| LogForging.cs:21:21:21:43 | ... + ... | LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:21:21:21:43 | ... + ... | This log entry depends on a $@. | LogForging.cs:18:27:18:49 | access to property QueryString | user-provided value |
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| LogForging.cs:27:50:27:72 | ... + ... | LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:27:50:27:72 | ... + ... | This log entry depends on a $@. | LogForging.cs:18:27:18:49 | access to property QueryString | user-provided value |
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| LogForging.cs:31:26:31:33 | access to local variable username | LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:31:26:31:33 | access to local variable username | This log entry depends on a $@. | LogForging.cs:18:27:18:49 | access to property QueryString | user-provided value |
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| LogForging.cs:29:50:29:72 | ... + ... | LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:29:50:29:72 | ... + ... | This log entry depends on a $@. | LogForging.cs:18:27:18:49 | access to property QueryString | user-provided value |
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| LogForging.cs:33:26:33:33 | access to local variable username | LogForging.cs:18:27:18:49 | access to property QueryString : NameValueCollection | LogForging.cs:33:26:33:33 | access to local variable username | This log entry depends on a $@. | LogForging.cs:18:27:18:49 | access to property QueryString | user-provided value |
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| LogForgingAsp.cs:12:21:12:43 | ... + ... | LogForgingAsp.cs:8:32:8:39 | username : String | LogForgingAsp.cs:12:21:12:43 | ... + ... | This log entry depends on a $@. | LogForgingAsp.cs:8:32:8:39 | username | user-provided value |

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