CVE-2004-0077 in Linux
Summary
by MITRE
The do_mremap function for the mremap system call in Linux 2.2 to 2.2.25, 2.4 to 2.4.24, and 2.6 to 2.6.2, does not properly check the return value from the do_munmap function when the maximum number of VMA descriptors is exceeded, which allows local users to gain root privileges, a different vulnerability than CAN-2003-0985.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability identified as CVE-2004-0077 represents a critical privilege escalation flaw within the Linux kernel's memory management subsystem. This issue affects kernel versions ranging from 2.2.0 through 2.2.25, 2.4.0 through 2.4.24, and 2.6.0 through 2.6.2, making it a widespread concern across multiple kernel generations. The vulnerability specifically resides in the do_mremap function which handles the mremap system call, a mechanism that allows processes to resize memory mappings. The flaw stems from inadequate error handling within the kernel's memory management logic, creating a path for local attackers to escalate privileges to root level access.
The technical root cause of this vulnerability lies in the improper validation of return values from the do_munmap function during memory remapping operations. When the system approaches or exceeds the maximum number of Virtual Memory Area (VMA) descriptors, the do_munmap function returns an error code indicating failure. However, the do_mremap function fails to properly check this return value before proceeding with subsequent operations. This oversight creates a condition where memory management operations can proceed despite resource limitations, ultimately allowing an attacker to manipulate kernel memory structures in ways that bypass normal privilege controls. The vulnerability operates under the Common Weakness Enumeration classification of CWE-252, which deals with "Unchecked Return Value" conditions where functions fail to properly validate their return codes, leading to unexpected program behavior.
The operational impact of this vulnerability is severe and directly enables local privilege escalation attacks. An attacker with normal user privileges can exploit this flaw to gain root access to the system, effectively compromising the entire machine's security posture. The attack vector requires local system access but does not need special privileges or network connectivity, making it particularly dangerous in multi-user environments where users might have legitimate access to system resources. The vulnerability's exploitation process typically involves carefully crafted memory mapping operations that trigger the specific code path where the return value check fails. This allows attackers to manipulate kernel memory structures, potentially leading to arbitrary code execution with kernel-level privileges. The flaw also aligns with ATT&CK technique T1068, which describes "Local Privilege Escalation" through kernel exploits, and specifically relates to the use of memory management vulnerabilities for privilege elevation.
Mitigation strategies for CVE-2004-0077 primarily focus on kernel version updates and system hardening measures. The most effective solution involves upgrading to kernel versions that contain the fix for this vulnerability, which was implemented in subsequent releases beyond the affected ranges. System administrators should prioritize applying security patches from their distribution vendors to address this issue. Additional protective measures include implementing kernel security modules such as SELinux or AppArmor to limit the impact of potential exploitation, monitoring for unusual memory management patterns, and restricting local user access where possible. The vulnerability serves as a critical reminder of the importance of proper error handling in kernel code and the potential consequences of unchecked return values in security-sensitive contexts. Organizations should also consider implementing runtime monitoring solutions that can detect anomalous memory management behaviors indicative of exploitation attempts.