CVE-2004-1001 in Shadow
Summary
by MITRE
Unknown vulnerability in the passwd_check function in Shadow 4.0.4.1, and possibly other versions before 4.0.5, allows local users to conduct unauthorized activities when an error from a pam_chauthtok function call is not properly handled.
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Analysis
by VulDB Data Team • 06/30/2019
The vulnerability identified as CVE-2004-1001 resides within the Shadow password management system version 4.0.4.1 and potentially earlier releases, representing a critical flaw in the passwd_check function that enables local users to exploit improper error handling mechanisms. This vulnerability falls under the category of privilege escalation and unauthorized access, where the failure to properly manage error conditions from the pam_chauthtok function creates exploitable pathways for malicious actors. The Shadow password suite serves as a fundamental component in unix-like operating systems for managing user authentication and password changes, making this vulnerability particularly concerning for system security. The specific technical flaw manifests when the pam_chauthtok function, which is responsible for changing user authentication tokens, returns an error condition that the passwd_check function fails to adequately process or validate, potentially allowing unauthorized modifications to user credentials or access controls.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise potential, as local users who can manipulate the error handling behavior may gain unauthorized access to accounts or escalate their privileges within the system. This flaw represents a classic case of inadequate error handling that can be exploited through carefully crafted inputs or system conditions that trigger the specific error path. The vulnerability's exploitation typically involves scenarios where authentication token changes fail in predictable ways, allowing attackers to bypass normal authentication controls or manipulate the authentication flow. From a cybersecurity perspective, this vulnerability aligns with CWE-252, which addresses "Unchecked Return Value" conditions where programs fail to properly handle error conditions returned by system calls or library functions. The attack vector is primarily local, requiring physical or account access to the target system, but the potential for privilege escalation means that even limited access can result in significant system compromise.
Mitigation strategies for CVE-2004-1001 should prioritize immediate patching of the Shadow package to version 4.0.5 or later, where the error handling in the passwd_check function has been corrected to properly validate and process return values from pam_chauthtok calls. System administrators should implement comprehensive monitoring of authentication-related error logs to detect potential exploitation attempts, as the improper error handling may generate specific log patterns that indicate attempted exploitation. The vulnerability demonstrates the critical importance of robust error handling in security-critical code paths, particularly within authentication modules that directly control access to system resources. Organizations should conduct thorough security assessments of their authentication infrastructure to identify similar error handling weaknesses in other components, as this vulnerability exemplifies how seemingly minor code flaws can create significant security risks. Additionally, implementing proper input validation and ensuring that all system calls return proper error codes can prevent similar vulnerabilities from emerging in other security-sensitive applications. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of authentication mechanisms to gain unauthorized access or elevated privileges within a compromised system.