mcp-server-semgrep/semgrep-rules/csharp/lang/security/xxe/xmldocument-unsafe-parser-override.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: xmldocument-unsafe-parser-override
  mode: taint
  pattern-sources:
  - patterns:
    - focus-metavariable: $ARG
    - pattern-inside: |
        public $T $M(...,string $ARG,...){...}
  pattern-sinks:
  - patterns:
    - pattern: |
        $XMLDOCUMENT.$METHOD(...)
    - pattern-inside: |
        XmlDocument $XMLDOCUMENT = new XmlDocument(...);
        ...
        $XMLDOCUMENT.XmlResolver = new XmlUrlResolver(...);
        ...  
  message: XmlReaderSettings found with DtdProcessing.Parse on an XmlReader handling a string argument
    from a public method. Enabling Document Type Definition (DTD) parsing may cause XML External Entity
    (XXE) injection if supplied with user-controllable data.
  languages:
  - csharp
  severity: WARNING
  metadata:
    category: security
    references:
    - https://www.jardinesoftware.net/2016/05/26/xxe-and-net/
    - https://docs.microsoft.com/en-us/dotnet/api/system.xml.xmldocument.xmlresolver?view=net-6.0#remarks
    technology:
    - .net
    - xml
    cwe:
    - 'CWE-611: Improper Restriction of XML External Entity Reference'
    owasp:
    - A04:2017 - XML External Entities (XXE)
    - A05:2021 - Security Misconfiguration
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - vuln
    impact: MEDIUM
    likelihood: LOW
    confidence: MEDIUM