CVE-2003-0124 in man
Summary
by MITRE
man before 1.5l allows attackers to execute arbitrary code via a malformed man file with improper quotes, which causes the my_xsprintf function to return a string with the value "unsafe," which is then executed as a program via a system call if it is in the search path of the user who runs man.
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Analysis
by VulDB Data Team • 11/12/2024
The vulnerability described in CVE-2003-0124 represents a critical buffer overflow and code execution flaw within the man command utility version 1.5l and earlier. This issue arises from improper handling of malformed man pages that contain specially crafted quotes, creating a dangerous condition where user-controlled input can be interpreted as executable commands. The vulnerability specifically targets the my_xsprintf function which fails to properly validate or sanitize input strings, resulting in the return of an "unsafe" string value that can be subsequently executed through system calls. This represents a classic command injection vulnerability where untrusted data flows directly into executable contexts without proper sanitization or validation.
The technical implementation of this flaw demonstrates a failure in input validation and string handling within the man command's parsing logic. When an attacker crafts a malformed man file containing improper quote sequences, the my_xsprintf function processes this input and returns a string with the literal value "unsafe" instead of properly handling the malformed input. This unsafe string is then passed through a system call execution pathway, allowing arbitrary code execution with the privileges of the user running the man command. The vulnerability is particularly dangerous because it leverages the common man command execution path and can be triggered simply by viewing a maliciously crafted man page, making it highly exploitable in environments where users frequently access documentation files.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise when attackers can control the content of man pages or influence the documentation environment. Since the man command is typically available to all users and often executed with elevated privileges during system administration tasks, this vulnerability can be exploited by both local and remote attackers. The attack vector is particularly concerning because it requires minimal user interaction beyond viewing what appears to be legitimate documentation, making it difficult to detect and prevent through conventional security measures. The vulnerability also aligns with attack patterns described in the ATT&CK framework under privilege escalation and command execution techniques, where adversaries leverage legitimate system tools to execute malicious code.
Mitigation strategies for this vulnerability must address both the immediate code execution risk and the underlying input validation failures. System administrators should immediately upgrade to man command versions that have patched this vulnerability, specifically versions 1.5.2 and later which contain proper input sanitization and validation routines. Additionally, implementing proper file access controls and restricting write permissions on man page directories can prevent attackers from placing malicious man files in system paths. The vulnerability demonstrates the importance of following secure coding practices and adhering to CWE guidelines for buffer overflow prevention and input validation. Organizations should also consider implementing automated scanning for vulnerable man command versions and establishing proper documentation access controls to prevent unauthorized modification of system documentation files that could be exploited through this attack vector.