CVE-2013-7267 in Linux
Summary
by MITRE
The atalk_recvmsg function in net/appletalk/ddp.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 identified as CVE-2013-7267 resides within the Linux kernel's AppleTalk protocol implementation, specifically in the atalk_recvmsg function located in net/appletalk/ddp.c. This flaw represents a classic case of uninitialized memory access that can lead to information disclosure, making it particularly dangerous for local attackers who can leverage it to extract sensitive data from kernel memory spaces. The vulnerability affects Linux kernel versions prior to 3.12.4, indicating a long-standing issue that was not addressed until a relatively recent kernel release. The AppleTalk protocol implementation is part of the kernel's network stack and handles data link protocol communications between Apple devices, making this vulnerability particularly concerning for systems that support or interface with legacy Apple networking protocols.
The technical root cause of this vulnerability stems from improper initialization of a length value within the atalk_recvmsg function. When processing socket receive operations through recvfrom, recvmmsg, or recvmsg system calls, the function updates a length field without first ensuring that the associated data structure containing the actual message buffer has been properly initialized. This creates a scenario where the length value may contain garbage data from previous kernel memory operations, leading to potential information leakage when the function attempts to use this uninitialized value for memory operations or buffer management. The flaw is categorized under CWE-457 as "Use of Uninitialized Variable" which directly relates to improper initialization of variables that can result in information disclosure. This type of vulnerability is particularly insidious because it operates at the kernel level where memory access patterns can reveal sensitive information including cryptographic keys, passwords, or other confidential data stored in kernel memory.
The operational impact of CVE-2013-7267 is significant for local attackers who have access to the system, as it allows them to perform information disclosure attacks against the kernel memory space. Attackers can exploit this vulnerability by making specific socket system calls that trigger the atalk_recvmsg function, potentially extracting sensitive information that was previously stored in memory locations that were not properly cleared or initialized. This information disclosure can lead to various downstream security consequences including privilege escalation opportunities, where attackers might obtain kernel memory contents that could reveal system internals, security credentials, or other confidential information. The vulnerability is particularly dangerous because it requires no special privileges beyond local access, making it a common target for attackers who have already compromised a system or are attempting to gain further access through information gathering. From an ATT&CK perspective, this vulnerability maps to T1005 (Data from Local System) and T1059 (Command and Scripting Interpreter) as it enables attackers to extract system information and potentially leverage that information for further attacks.
Mitigation strategies for CVE-2013-7267 primarily involve upgrading to Linux kernel versions 3.12.4 or later where the vulnerability has been patched. The fix implemented in the patched versions ensures proper initialization of the length value before it is used in the atalk_recvmsg function, preventing the information disclosure that occurred due to uninitialized memory access. System administrators should also consider disabling AppleTalk protocol support entirely if it is not required for their specific use case, which can be achieved through kernel configuration options or module loading restrictions. Additionally, monitoring for unusual socket activity patterns that might indicate exploitation attempts can provide early detection of potential attacks. Organizations should also implement comprehensive patch management procedures to ensure all systems are updated promptly when security vulnerabilities like this are discovered, as the vulnerability affects a core kernel component that is present on virtually all Linux systems. The remediation process should include thorough testing of kernel updates to ensure compatibility with existing applications and system configurations, while also verifying that the patch correctly addresses the uninitialized variable issue in the AppleTalk protocol implementation.