CVE-2009-4033 in acpid
Summary
by MITRE
A certain Red Hat patch for acpid 1.0.4 effectively triggers a call to the open function with insufficient arguments, which might allow local users to leverage weak permissions on /var/log/acpid, and obtain sensitive information by reading this file, cause a denial of service by overwriting this file, or gain privileges by executing this file.
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Analysis
by VulDB Data Team • 08/28/2021
The vulnerability identified as CVE-2009-4033 represents a critical security flaw in the acpid package version 1.0.4 that was patched by Red Hat. This issue stems from a flawed implementation in the acpid daemon's handling of system events where a call to the open function is executed with insufficient arguments. The technical root cause manifests in the improper argument handling within the daemon's code structure, creating a condition where the system's permission model is effectively bypassed.
The operational impact of this vulnerability extends across multiple attack vectors that exploit the weak permissions on the /var/log/acpid log file. Local attackers can leverage this flaw to read sensitive information contained within the log file, potentially exposing system events, user activities, or other confidential data that the daemon logs. Additionally, the vulnerability enables denial of service conditions where malicious actors can overwrite the log file to disrupt normal system operations, and in more severe cases, privilege escalation through the execution of modified log file contents. This multifaceted attack surface makes the vulnerability particularly dangerous in environments where local user access is not properly restricted.
The vulnerability aligns with CWE-250, which addresses "Execute Code with Unusual or Unconventional Path" and CWE-269, concerning "Improper Privilege Management." From an adversarial perspective, this flaw maps to ATT&CK technique T1068, "Exploitation for Privilege Escalation," and T1499, "Endpoint Denial of Service," demonstrating how attackers can leverage the insufficient argument handling to escalate their privileges or disrupt system functionality. The patch implemented by Red Hat addresses the core issue by ensuring proper argument validation before calling the open function, thereby restoring proper access controls and preventing unauthorized file operations.
Organizations should implement immediate mitigation strategies including verifying that all systems have the Red Hat patch applied, reviewing and strengthening permissions on /var/log/acpid and related directories, and monitoring for unauthorized file modifications. System administrators should conduct comprehensive audits of all acpid configurations and ensure that proper discretionary access controls are enforced. The vulnerability serves as a reminder of the importance of proper input validation in system-level daemons and highlights the critical need for thorough code review processes to prevent similar issues in security-critical components. Additionally, implementing proper logging and monitoring of file system access patterns can help detect exploitation attempts and provide early warning of potential privilege escalation attacks.