CVE-2005-0240 in AIX
Summary
by MITRE
Format string vulnerability in chdev on IBM AIX 5.2 allows local users to execute arbitrary code via format string specifiers in a command line argument, which is not properly handled when printing an error message.
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Analysis
by VulDB Data Team • 01/14/2018
The vulnerability identified as CVE-2005-0240 represents a critical format string flaw within the chdev command on IBM AIX 5.2 operating systems. This issue arises from improper handling of user-supplied input when the command processes error messages, creating a pathway for malicious code execution. The chdev utility, which serves to change device characteristics in AIX environments, becomes a vector for privilege escalation when local attackers exploit this weakness through carefully crafted command line arguments containing format specifiers.
From a technical perspective, the vulnerability stems from the command's failure to properly sanitize or validate command line parameters before using them in printf-style functions. When an error occurs during device configuration, the chdev command attempts to display an error message containing user-provided data without adequate input validation. This allows attackers to inject format specifiers such as %s, %x, or %n that can manipulate the program's execution flow and potentially execute arbitrary code with the privileges of the executing process. The flaw specifically aligns with CWE-134, which categorizes format string vulnerabilities as weaknesses that occur when a program uses user-supplied data as a format string without proper validation.
The operational impact of this vulnerability extends beyond simple code execution, as it provides local attackers with a means to escalate privileges within the AIX environment. Since chdev typically operates with elevated privileges due to its system administration functions, successful exploitation could lead to complete system compromise. Attackers could leverage this vulnerability to gain unauthorized access to critical system resources, modify device configurations, or establish persistent backdoors. The vulnerability's local nature means that an attacker must already have access to the system, but the privilege escalation aspect makes it particularly dangerous in environments where local access is possible.
Security professionals should consider this vulnerability in the context of broader attack frameworks such as MITRE ATT&CK, where it maps to techniques involving privilege escalation and execution of malicious code. The vulnerability demonstrates how seemingly benign system utilities can become attack vectors when proper input validation is omitted. Organizations should implement immediate mitigations including applying the vendor-supplied patches, restricting local access to system administration tools, and monitoring for suspicious command line usage patterns. Additionally, system administrators should consider implementing input validation controls and conducting regular security assessments to identify similar vulnerabilities in other system utilities that may be susceptible to format string attacks. The remediation approach should also include comprehensive testing to ensure that patched versions maintain system functionality while eliminating the exploitability of the vulnerability.