CVE-2014-8764 in DokuWiki
Summary
by MITRE
DokuWiki 2014-05-05a and earlier, when using Active Directory for LDAP authentication, allows remote attackers to bypass authentication via a user name and password starting with a null (\0) character, which triggers an anonymous bind.
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Analysis
by VulDB Data Team • 02/24/2022
The vulnerability identified as CVE-2014-8764 affects DokuWiki versions up to and including 2014-05-05a and represents a critical authentication bypass flaw that specifically impacts systems utilizing Active Directory for LDAP authentication. This weakness stems from improper handling of user credentials containing null characters within the authentication process, creating a pathway for unauthorized access that directly undermines the security model of the application. The vulnerability is particularly concerning because it allows remote attackers to exploit the authentication mechanism without requiring valid credentials, effectively rendering the authentication system ineffective against this specific attack vector.
The technical root cause of this vulnerability lies in how DokuWiki processes user authentication requests when Active Directory is configured as the LDAP backend. When a username or password begins with a null character, the application fails to properly sanitize or validate these inputs before establishing the LDAP connection. This flaw triggers an anonymous bind operation within the LDAP protocol, which occurs when the client sends an empty or null username and password to the directory server. The LDAP protocol specification allows for anonymous binds when authentication credentials are not provided or are null, and DokuWiki's implementation does not adequately prevent this scenario from occurring during the authentication flow.
The operational impact of this vulnerability is severe as it enables attackers to gain unauthorized access to DokuWiki instances without needing legitimate user credentials. This authentication bypass can be executed remotely, making it particularly dangerous for web-based applications. An attacker can simply craft a login request with a username starting with a null character followed by any password, or manipulate the password field to begin with a null character, and successfully establish a valid session. This vulnerability directly violates the principle of least privilege and can lead to complete compromise of the wiki instance, potentially allowing attackers to modify content, add malicious pages, or escalate privileges to administrative functions.
The vulnerability maps to CWE-287, which addresses improper authentication issues in software systems, and aligns with ATT&CK technique T1078.004 for valid accounts and T1566.002 for spearphishing attachments, as the bypass can be achieved through simple credential manipulation without requiring complex social engineering. Organizations using DokuWiki with Active Directory authentication should prioritize immediate remediation of this vulnerability, as it can be exploited without requiring advanced technical skills or significant resources. The fix typically involves implementing proper input validation and sanitization of authentication credentials to prevent null characters from being processed in LDAP bind operations. Additionally, administrators should consider implementing additional security measures such as rate limiting and monitoring for unusual authentication patterns that might indicate exploitation attempts.
This vulnerability demonstrates the critical importance of proper input validation in authentication systems and highlights how seemingly minor implementation flaws can have significant security implications. The issue particularly affects organizations that rely heavily on LDAP-based authentication mechanisms, where the interaction between different authentication protocols and application-level input handling can create unexpected security gaps. Security teams should conduct comprehensive audits of their authentication systems to identify similar vulnerabilities and ensure that all user inputs are properly validated before being processed by backend services. The remediation process should include not only patching the specific vulnerability but also implementing broader security controls to prevent similar issues from occurring in other components of the authentication stack.