CVE-2012-1109 in mwlib
Summary
by MITRE
mwlib 0.13 through 0.13.4 has a denial of service vulnerability when parsing #iferror magic functions
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Analysis
by VulDB Data Team • 02/13/2024
The vulnerability identified as CVE-2012-1109 affects mwlib versions 0.13 through 0.13.4 and represents a denial of service condition that manifests during the parsing of #iferror magic functions. This issue resides within the mwlib library which is commonly used for processing MediaWiki markup and related content. The vulnerability stems from insufficient input validation and error handling mechanisms within the parsing logic that processes these specific magic functions. When maliciously crafted input containing #iferror directives is processed, the parser enters an infinite loop or consumes excessive computational resources, leading to system unresponsiveness and service disruption.
The technical flaw manifests in the parser's inability to properly handle malformed or specially constructed #iferror magic function calls. This vulnerability falls under the category of improper input validation as defined by CWE-20, where the system fails to adequately sanitize or validate user-provided input before processing. The parsing routine does not implement proper bounds checking or recursion limits when encountering these magic functions, allowing an attacker to craft inputs that cause the parser to consume excessive memory or processing cycles. The issue is particularly concerning because it can be triggered through user-submitted content that gets processed by the mwlib library, making it exploitable in web applications that utilize this library for content rendering.
The operational impact of this vulnerability extends beyond simple service disruption as it can be leveraged to exhaust system resources and potentially cause cascading failures in applications that rely on mwlib for content processing. When exploited, the denial of service condition can affect web servers, content management systems, or any application that processes MediaWiki markup through this library. The vulnerability is particularly dangerous in multi-tenant environments or public-facing applications where users can submit content that gets processed by the affected library. Attackers can exploit this weakness to consume server resources, leading to increased latency, application crashes, or complete service unavailability, which directly impacts user experience and system reliability.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and resource limiting mechanisms within the parsing routines. Organizations should immediately upgrade to mwlib versions that have patched this vulnerability, as the maintainers have released updated versions with improved error handling and input validation. Additionally, implementing rate limiting and resource monitoring can help detect and prevent exploitation attempts before they cause significant damage. The fix typically involves adding proper bounds checking and recursion depth limits when processing magic functions, ensuring that the parser terminates execution within reasonable timeframes even when encountering malformed input. Security practitioners should also consider implementing application firewalls or content filters that can detect and block suspicious input patterns that might trigger this vulnerability, aligning with defensive techniques outlined in the MITRE ATT&CK framework under the application layer attack patterns.