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attack-surface.md

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Attack Surface Analysis for robbiehanson/xmppframework

Attack Surface: XML External Entity (XXE) Injection

  • Description: Attackers inject malicious XML containing external entity references to access local files, internal network resources, or cause denial of service.
  • xmppframework Contribution: The framework relies on libxml2 for XML parsing, which, if misconfigured or outdated, is vulnerable to XXE. xmppframework directly handles the XML parsing, making it the vulnerable component.
  • Example: An attacker sends a crafted XMPP message containing: 
    <!DOCTYPE foo [
  <!ELEMENT foo ANY >
  <!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
<message to='[email protected]'>
  <body>&xxe;</body>
</message>
  • Impact:
    • Disclosure of sensitive local files (e.g., /etc/passwd, configuration files).
    • Access to internal network services (SSRF).
    • Denial of service (DoS) by exhausting server resources.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Developer) Verify that libxml2 is configured within xmppframework to disable external entity resolution. Check for the use of XML_PARSE_NOENT and XML_PARSE_NONET flags during XML parser initialization. This is the primary defense and is the responsibility of the code using libxml2 (i.e., xmppframework or your wrapper around it).
    • (Developer) Keep libxml2 (as used by xmppframework) updated to the latest patched version.
    • (Developer) Implement strict input validation and sanitization on all incoming XML data after xmppframework has parsed it, rejecting unexpected elements or attributes.
    • (Developer/Operations) Use resource limits (memory, CPU) on XML parsing (within the context of how xmppframework uses it) to mitigate DoS.

Attack Surface: Stanza Smuggling

  • Description: Attackers exploit differences in how XMPP servers and clients parse stanzas to inject malicious payloads or bypass security controls.
  • xmppframework Contribution: The framework is directly responsible for constructing and parsing XMPP stanzas. Bugs in this core functionality create the vulnerability.
  • Example: An attacker sends a malformed stanza with crafted whitespace or character encoding that is interpreted differently by the client (using xmppframework) and the server. This allows the attacker to inject a hidden command or bypass a filter. The specifics depend on parsing differences.
  • Impact:
    • Bypassing security filters (e.g., message content filters).
    • Injecting malicious commands or data.
    • Potentially achieving remote code execution (RCE) in severe cases.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developer) Keep xmppframework updated to the latest version. The framework developers are responsible for addressing protocol-level parsing issues.
    • (Developer) Implement robust input validation after xmppframework has parsed the stanza. Don't rely solely on the framework. Check for unexpected elements, attributes, and data types.

Attack Surface: JID Spoofing

  • Description: Attackers impersonate other users by forging their Jabber IDs (JIDs).
  • xmppframework Contribution: The framework directly handles JID parsing and, ideally, should provide mechanisms for validation. Weaknesses in its handling of JIDs create the vulnerability.
  • Example: An attacker sends a message with a from attribute set to [email protected], even if they don't control that account. If xmppframework doesn't provide the authenticated JID for comparison, or if the application developer doesn't use it, spoofing is possible.
  • Impact:
    • Social engineering attacks.
    • Unauthorized access to resources.
    • Reputational damage.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developer) Ensure the application explicitly verifies that the from attribute of incoming messages matches the authenticated JID of the sender. The framework must provide a way to access the authenticated JID; use that API. Do not trust the from attribute in the raw stanza without verification against the authenticated identity provided by the framework.

Attack Surface: TLS Downgrade/Misconfiguration

  • Description: Attackers force the client and server to use weaker or no TLS encryption, enabling man-in-the-middle (MITM) attacks.
  • xmppframework Contribution: The framework directly handles TLS negotiation and connection establishment. Its configuration and implementation are crucial.
  • Example: An attacker intercepts the initial XMPP connection and modifies the server's advertised features to remove TLS support. If xmppframework doesn't enforce TLS, the connection proceeds unencrypted.
  • Impact:
    • Interception and modification of XMPP traffic.
    • Credential theft.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Developer) Explicitly configure xmppframework to require TLS 1.2 or higher. Use the framework's API to enforce this.
    • (Developer) Specify a strong cipher suite via xmppframework's configuration options.
    • (Developer) Always verify the server's certificate using the APIs provided by xmppframework. Implement certificate pinning if appropriate, again using the framework's capabilities if available.

Attack Surface: Weak SASL Authentication

  • Description: Using weak SASL mechanisms (e.g., PLAIN, DIGEST-MD5) exposes user credentials.
  • xmppframework Contribution: The framework directly implements and manages the SASL authentication process. Allowing weak mechanisms, or not providing a way to restrict them, is a framework issue.
  • Example: If xmppframework allows the PLAIN mechanism, the password is sent in plain text (base64 encoded, but trivially decoded) over the connection.
  • Impact:
    • Credential theft.
    • Unauthorized account access.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developer) Configure xmppframework via its API to only allow strong SASL mechanisms (SCRAM-SHA-256 or SCRAM-SHA-512). Disable weaker mechanisms using the framework's configuration options. The framework must provide a way to control this.