CVE-2002-0735 in Squid Auth LDAP
Summary
by MITRE
Format string vulnerability in the logging() function in C-Note Squid LDAP authentication module (squid_auth_LDAP) 2.0.2 and earlier allows remote attackers to cause a denial of service and possibly execute arbitrary code by triggering log messages.
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Analysis
by VulDB Data Team • 07/06/2024
The vulnerability described in CVE-2002-0735 represents a critical format string flaw within the squid_auth_LDAP module of the C-Note Squid LDAP authentication system version 2.0.2 and earlier. This issue resides in the logging() function which processes authentication events and generates log entries for system monitoring and auditing purposes. The flaw occurs when the module fails to properly validate user-supplied input before incorporating it into log messages, creating an exploitable condition that can be leveraged by remote attackers to manipulate the application's behavior.
This format string vulnerability falls under the CWE-134 classification, which specifically addresses the use of untrusted data in format string functions. The technical implementation of this flaw allows attackers to inject format specifiers into log messages, potentially leading to arbitrary code execution or denial of service conditions. When the logging() function processes malformed input containing format specifiers such as %s, %d, or %x, the application may interpret these as instructions for reading from memory locations or performing other unintended operations, thereby exposing the system to exploitation.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially enable remote code execution on the affected system. Attackers who can trigger log messages through the LDAP authentication module can manipulate the format string parameters to read sensitive memory locations, overwrite critical system variables, or even execute arbitrary commands with the privileges of the running process. This creates a significant threat vector for systems relying on Squid proxy servers with LDAP authentication, as successful exploitation could allow attackers to gain unauthorized access to network resources or compromise the entire proxy infrastructure.
The attack surface for this vulnerability is particularly concerning as it affects the core authentication functionality of the Squid proxy server, which is commonly deployed in enterprise environments for web filtering, caching, and access control purposes. The vulnerability can be exploited by remote attackers without requiring authentication, making it especially dangerous in network environments where the proxy server is accessible from external networks. This characteristic aligns with ATT&CK technique T1190, which covers the exploitation of vulnerabilities in remote services to gain unauthorized access.
Mitigation strategies for this vulnerability should include immediate patching of the squid_auth_LDAP module to version 2.0.3 or later, which contains the necessary fixes for the format string handling. Organizations should also implement network segmentation to limit access to proxy servers and monitor log files for suspicious format string patterns. Additionally, the use of input validation and proper string formatting functions that do not rely on user-supplied data directly in format specifiers should be enforced. Security monitoring should include detection of potential exploitation attempts through analysis of log message patterns that might indicate format string manipulation attempts, as outlined in the MITRE ATT&CK framework's methodology for detecting privilege escalation techniques.