CVE-2016-10026 in Ikiwiki
Summary
by MITRE
ikiwiki 3.20161219 does not properly check if a revision changes the access permissions for a page on sites with the git and recentchanges plugins and the CGI interface enabled, which allows remote attackers to revert certain changes by leveraging permissions to change the page before the revision was made.
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Analysis
by VulDB Data Team • 10/28/2022
The vulnerability identified as CVE-2016-10026 affects ikiwiki version 3.20161219 and represents a significant access control flaw that undermines the security of collaborative wiki environments. This issue specifically manifests when systems employ the git and recentchanges plugins in conjunction with the CGI interface, creating a scenario where unauthorized users can manipulate page permissions through strategic timing of their actions. The vulnerability stems from inadequate validation mechanisms that fail to properly verify whether revision operations alter access permissions, allowing malicious actors to exploit temporal gaps in the permission checking process.
The technical implementation of this flaw occurs within the permission validation logic of ikiwiki's revision handling system. When a user attempts to modify a page, the system should verify that the user possesses appropriate authorization not only for the modification itself but also for any potential permission changes that might result from the revision. However, the software fails to perform this comprehensive check, particularly in environments where git versioning and recentchanges tracking are active. This oversight creates a race condition where an attacker can submit a revision that reverts specific changes by exploiting the window between when the original modification is processed and when the permission validation occurs.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to effectively undo legitimate modifications while maintaining their own access privileges. This capability allows adversaries to selectively revert content changes that they lack direct permission to modify, effectively bypassing the intended access control mechanisms. The vulnerability is particularly dangerous in collaborative environments where multiple users contribute content, as it can be used to remove sensitive information or prevent legitimate contributors from making their changes. Attackers can leverage this flaw to manipulate the content history and potentially disrupt the integrity of the wiki system.
From a cybersecurity perspective, this vulnerability aligns with CWE-284, which addresses improper access control, and represents a classic example of a privilege escalation vulnerability that can be exploited through timing-based attacks. The flaw also relates to ATT&CK technique T1078 which covers valid accounts and T1566 which covers spearphishing with a malicious attachment, as attackers may need to gain initial access before exploiting this specific permission bypass. Organizations using ikiwiki in production environments should consider this vulnerability as part of their broader security posture assessment, particularly those with collaborative editing environments where multiple user roles exist.
Mitigation strategies for CVE-2016-10026 require immediate attention through software updates to the latest stable versions of ikiwiki that address the permission validation flaw. System administrators should also implement additional monitoring of page modification activities, particularly focusing on recentchanges and git commit logs that might indicate unauthorized permission manipulations. The recommended approach includes disabling the CGI interface when it is not strictly required, implementing more granular access controls, and establishing regular audits of page permission changes. Additionally, organizations should consider implementing automated alerting mechanisms that can detect suspicious patterns in revision operations, particularly those that attempt to revert changes shortly after they were made, as this behavior often indicates exploitation attempts of this specific vulnerability.