CVE-2013-7265 in Linux
Summary
by MITRE
The pn_recvmsg function in net/phonet/datagram.c in the Linux kernel before 3.12.4 updates a certain length value before ensuring that an associated data structure has been initialized, which allows local users to obtain sensitive information from kernel stack memory via a (1) recvfrom, (2) recvmmsg, or (3) recvmsg system call.
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Analysis
by VulDB Data Team • 06/09/2021
The vulnerability identified as CVE-2013-7265 resides within the Linux kernel's phonet subsystem, specifically in the pn_recvmsg function located in net/phonet/datagram.c. This flaw represents a classic case of improper initialization followed by information disclosure, where the kernel fails to properly validate data structure state before processing system calls. The vulnerability affects Linux kernel versions prior to 3.12.4 and presents a significant security risk due to its potential for local privilege escalation through information leakage from kernel memory space.
The technical implementation of this vulnerability stems from a sequence of operations that violates fundamental security principles in kernel programming. The pn_recvmsg function processes incoming messages for the phonet protocol family, which is used for communication between applications and the kernel's phonet subsystem. During the processing of recvfrom, recvmmsg, or recvmsg system calls, the function updates a length value before verifying that the associated data structure has been properly initialized. This premature update creates a window where uninitialized memory values can be exposed to user-space applications through the system call interface.
This vulnerability directly maps to CWE-248, an improper initialization weakness, and can be categorized under the broader ATT&CK technique T1063 for "Obtain Capabilities" through information gathering. The flaw allows local users to extract sensitive kernel stack memory contents, potentially including cryptographic keys, session tokens, or other confidential data that should remain protected within kernel space. The information disclosure occurs because the kernel's phonet implementation does not properly validate the state of internal data structures before using them in the context of user-space system calls, creating a path for memory leakage that bypasses normal kernel security boundaries.
The operational impact of CVE-2013-7265 extends beyond simple information disclosure, as the leaked kernel memory could contain critical system information that could be leveraged for further exploitation. An attacker with local access could potentially use this vulnerability to gather sufficient information to craft more sophisticated attacks against the system, including bypassing kernel security features or discovering system-specific configurations. The vulnerability affects all local users on the system regardless of their privilege level, making it particularly dangerous in multi-user environments where privilege separation is expected.
Mitigation strategies for this vulnerability center on applying the official kernel patch released with version 3.12.4, which corrects the initialization sequence in the pn_recvmsg function. System administrators should prioritize updating their kernel installations to address this issue promptly, as the vulnerability requires no special privileges beyond local access to exploit. Additional defensive measures include implementing strict access controls on systems where local users have elevated privileges, monitoring for unusual network activity that might indicate exploitation attempts, and maintaining comprehensive system logs that could help detect unauthorized access patterns. The fix ensures proper validation of data structure initialization before any memory operations occur, preventing the exposure of uninitialized kernel memory contents to user-space applications.