CVE-2002-0916 in msntauth
Summary
by MITRE
Format string vulnerability in the allowuser code for the Stellar-X msntauth authentication module, as distributed in Squid 2.4.STABLE6 and earlier, allows remote attackers to execute arbitrary code via format strings in the user name, which are not properly handled in a syslog call.
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Analysis
by VulDB Data Team • 05/30/2019
The vulnerability identified as CVE-2002-0916 represents a critical format string vulnerability within the Stellar-X msntauth authentication module of Squid proxy software version 2.4.STABLE6 and earlier. This flaw exists in the allowuser code component that processes user authentication requests, specifically when handling user names passed through the authentication mechanism. The vulnerability stems from improper input validation and sanitization of user-provided data within the syslog function call, creating a path for malicious exploitation that can lead to arbitrary code execution on the affected system.
The technical implementation of this vulnerability occurs when the authentication module receives a user name containing format specifiers such as %s, %d, or other format string directives. These specifiers are not properly escaped or sanitized before being passed to the syslog function, which interprets them as format string directives rather than literal text. This misinterpretation allows attackers to craft malicious user names that can manipulate the syslog function's behavior, potentially leading to stack pointer corruption, information disclosure, or code execution. The vulnerability is classified under CWE-134 as "Use of Externally-Controlled Format String," which is a well-documented weakness in software security that has been consistently identified as a high-risk vulnerability across multiple security frameworks.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary code on the target system with the privileges of the Squid proxy process. This can result in complete system compromise, data exfiltration, or establishment of persistent backdoors within the network infrastructure. The attack vector is particularly dangerous because it requires no local access or authentication, making it a remote code execution vulnerability that can be exploited from anywhere on the internet. The vulnerability affects organizations using older versions of Squid proxy software, which were commonly deployed in enterprise environments for web caching and authentication purposes, making it a significant threat to network security.
Security mitigation strategies for this vulnerability include immediate upgrade to Squid version 2.4.STABLE7 or later, which contains the necessary patches to address the format string handling issue. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable proxy servers to external threats. The remediation process should include thorough testing of the updated software to ensure compatibility with existing network configurations and authentication systems. Additionally, security monitoring should be enhanced to detect potential exploitation attempts through unusual syslog entries or authentication patterns. This vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter, as successful exploitation would enable attackers to execute arbitrary commands on the compromised system, potentially leading to further lateral movement within the network infrastructure.