CVE-2016-9646 in Ikiwiki
Summary
by MITRE
ikiwiki before 3.20161229 incorrectly called the CGI::FormBuilder->field method (similar to the CGI->param API that led to Bugzilla s CVE-2014-1572), which can be abused to lead to commit metadata forgery.
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Analysis
by VulDB Data Team • 07/21/2020
The vulnerability identified as CVE-2016-9646 affects ikiwiki versions prior to 3.20161229 and represents a critical security flaw in the handling of CGI form data processing. This issue stems from the improper invocation of the CGI::FormBuilder->field method, which mirrors the problematic pattern found in Bugzilla's CVE-2014-1572 vulnerability. The flaw exists within the core web application framework that processes user input through CGI interfaces, creating a pathway for malicious actors to manipulate form field data in ways that were not properly validated or sanitized.
The technical implementation of this vulnerability exploits the similarity between CGI::FormBuilder->field and CGI->param APIs, which are commonly used for retrieving and processing form data in web applications. When ikiwiki processes form submissions, it incorrectly handles the field method calls, allowing attackers to inject crafted data that bypasses normal input validation mechanisms. This improper handling occurs at the application layer where user-supplied parameters are processed and subsequently used to generate commit metadata within the wiki system. The vulnerability specifically targets the metadata generation process, which is critical for maintaining the integrity and provenance of changes within the wiki's version control system.
The operational impact of this vulnerability is significant as it enables commit metadata forgery, which undermines the trust model of the wiki system. Attackers can manipulate the authorship information, timestamps, and other metadata associated with commits, potentially leading to false attribution of changes, disruption of audit trails, and compromise of the system's integrity. This type of attack falls under the category of data integrity violations and can be particularly damaging in collaborative environments where trust in commit history is essential. The vulnerability directly relates to CWE-20, which addresses improper input validation, and can be mapped to ATT&CK technique T1566 for social engineering through manipulation of data integrity.
Mitigation strategies for this vulnerability require immediate patching of ikiwiki to version 3.20161229 or later, which contains the necessary fixes for proper CGI form data handling. Organizations should also implement additional input validation measures and monitor commit logs for signs of metadata manipulation. The fix addresses the root cause by properly sanitizing and validating form field data before it is processed into commit metadata, ensuring that user-supplied input cannot be used to forge system-generated information. Security teams should also consider implementing automated monitoring for unusual patterns in commit metadata and establish proper access controls to limit the impact of potential exploitation.