CVE-2008-0731 in AppArmor
Summary
by MITRE
The Linux kernel before 2.6.18.8-0.8 in SUSE openSUSE 10.2 does not properly handle failure of an AppArmor change_hat system call, which might allow attackers to trigger the unconfining of an apparmored task.
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Analysis
by VulDB Data Team • 04/08/2017
The vulnerability described in CVE-2008-0731 represents a critical weakness in the Linux kernel's AppArmor security module implementation that existed in versions prior to 2.6.18.8-0.8 within SUSE openSUSE 10.2. This flaw specifically targets the change_hat system call functionality which is a core component of AppArmor's privilege management system. The issue stems from inadequate error handling mechanisms during the transition of security contexts, creating a potential pathway for malicious actors to bypass security restrictions that should otherwise confine applications and processes.
The technical flaw manifests when the AppArmor change_hat system call fails to properly validate or handle error conditions during security context transitions. This failure creates a race condition or state inconsistency that allows an attacker to manipulate the security framework and effectively unconstrain processes that should remain confined. The vulnerability operates at the kernel level where AppArmor policies are enforced, making it particularly dangerous as it undermines the fundamental security boundaries that separate privileged and unprivileged execution contexts. This represents a classic example of improper error handling that leads to security escalation, aligning with CWE-704 which categorizes improper error handling as a security weakness.
The operational impact of this vulnerability is significant for systems running the affected kernel versions, as it provides attackers with a method to circumvent mandatory access controls that are designed to limit the potential damage from compromised applications. An attacker who successfully exploits this vulnerability could potentially escalate privileges, gain unauthorized access to sensitive system resources, or execute arbitrary code with elevated privileges. The risk is compounded by the fact that AppArmor is designed to provide additional security layers beyond traditional Unix permissions, and this flaw effectively neutralizes those protections. The vulnerability demonstrates a failure in the principle of least privilege and represents a direct violation of the security model that AppArmor is intended to enforce.
Mitigation strategies for CVE-2008-0731 focus primarily on updating to patched kernel versions that properly handle AppArmor change_hat failures. System administrators should immediately apply the security patches released by SUSE for openSUSE 10.2, specifically targeting kernel versions 2.6.18.8-0.8 and later. Organizations should also implement comprehensive monitoring for unusual system behavior that might indicate exploitation attempts, including monitoring for unauthorized privilege escalation events or abnormal AppArmor policy changes. Additionally, implementing layered security approaches such as intrusion detection systems and regular security audits can help detect potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1068 which covers the use of privilege escalation techniques, and the remediation efforts should include reviewing and strengthening overall system hardening practices to prevent similar issues in other security modules. The incident highlights the importance of robust error handling in security-critical kernel components and demonstrates the necessity of thorough testing of security framework transitions.