CVE-2013-7271 in Linux
Summary
by MITRE
The x25_recvmsg function in net/x25/af_x25.c in the Linux kernel before 3.12.4 updates a certain length value without ensuring that an associated data structure has been initialized, which allows local users to obtain sensitive information from kernel memory via a (1) recvfrom, (2) recvmmsg, or (3) recvmsg system call.
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Analysis
by VulDB Data Team • 06/04/2021
The vulnerability described in CVE-2013-7271 represents a critical information disclosure flaw within the Linux kernel's X.25 protocol implementation. This issue affects kernel versions prior to 3.12.4 and specifically targets the x25_recvmsg function located in the net/x25/af_x25.c file. The flaw manifests when the kernel processes certain network system calls, creating a scenario where sensitive data from kernel memory may be inadvertently exposed to local users. The vulnerability is classified as a local privilege escalation vector since it requires local system access but can potentially reveal confidential information that should remain protected within kernel space.
The technical root cause of this vulnerability stems from improper initialization of data structures within the x25_recvmsg function. When processing recvfrom, recvmmsg, or recvmsg system calls, the kernel updates a length value without first ensuring that the associated data structure has been properly initialized. This uninitialized data structure contains residual information from previous operations, including potentially sensitive kernel memory contents. The flaw occurs because the kernel fails to validate that the target buffer has been adequately prepared before updating the length field, creating a pathway for information leakage. This type of vulnerability is categorized under CWE-457 as "Use of Uninitialized Variable" and represents a classic example of how improper state management can lead to information disclosure attacks.
The operational impact of CVE-2013-7271 extends beyond simple information disclosure, as it can potentially expose sensitive kernel data to local attackers who might leverage this information for further exploitation. Attackers could use the leaked memory contents to discover kernel addresses, stack contents, or other confidential information that could aid in bypassing security mechanisms such as kernel address space layout randomization. The vulnerability affects all local users on the system since it does not require network access or special privileges beyond basic system login. This makes it particularly concerning in multi-user environments where local access might be available to untrusted users. The attack vector is straightforward and requires only the execution of standard network system calls, making it accessible to attackers with minimal technical expertise.
Mitigation strategies for this vulnerability primarily focus on kernel version updates and system hardening measures. The most effective solution is upgrading to Linux kernel version 3.12.4 or later, where the vulnerability has been patched through proper initialization of the affected data structures. System administrators should also implement monitoring solutions to detect unusual patterns of system calls that might indicate exploitation attempts. The patch for this vulnerability follows standard security practices by ensuring proper initialization of variables before use, which aligns with the principle of least privilege and secure coding standards. Organizations should also consider implementing additional security controls such as mandatory access controls and kernel module signing to reduce the potential impact of such vulnerabilities. This type of vulnerability demonstrates the importance of thorough input validation and proper state management in kernel code, as outlined in various security frameworks including the ATT&CK framework's techniques for privilege escalation and information gathering.