CVE-2013-3223 in Linux
Summary
by MITRE
The ax25_recvmsg function in net/ax25/af_ax25.c in the Linux kernel before 3.9-rc7 does not initialize a certain data structure, which allows local users to obtain sensitive information from kernel stack memory via a crafted recvmsg or recvfrom system call.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/10/2021
The vulnerability identified as CVE-2013-3223 resides within the Linux kernel's AX.25 networking protocol implementation, specifically in the ax25_recvmsg function located in net/ax25/af_ax25.c. This flaw represents a classic information disclosure vulnerability that arises from improper initialization of kernel data structures. The AX.25 protocol is a network protocol designed for amateur radio packet communications, operating at the data link layer and providing reliable data transmission over radio channels. The vulnerability affects Linux kernel versions prior to 3.9-rc7, making it a significant concern for systems running older kernel versions that may be in production environments where upgrading is not immediately feasible.
The technical root cause of this vulnerability stems from the ax25_recvmsg function failing to properly initialize a data structure before utilizing it in kernel space. When a local user executes a crafted recvmsg or recvfrom system call against an AX.25 socket, the uninitialized data structure contains residual data from previous operations that may include sensitive kernel memory contents. This memory leakage occurs because the kernel does not explicitly zero out or initialize the structure fields before populating them with data from the network layer. The uninitialized memory may contain information such as kernel stack contents, memory addresses, or other sensitive data that could be accessed by the malicious user. This type of vulnerability aligns with CWE-457, which describes the use of uninitialized variables, and represents a common pattern in kernel security flaws where improper initialization leads to information disclosure.
The operational impact of this vulnerability is significant for local attackers who have access to the system, as it allows them to extract sensitive information from kernel memory through relatively simple system calls. Since the vulnerability is local in nature, it does not require network access or special privileges beyond normal user access, making it particularly dangerous in multi-user environments or when users have shell access to systems. The leaked information could potentially include kernel memory addresses, stack contents, or other sensitive data that could be used in subsequent attacks such as privilege escalation or bypassing kernel security features. This information leakage could also aid in developing more sophisticated attacks by providing attackers with insights into kernel memory layout and internal structures, thereby reducing the effectiveness of various kernel security mitigations such as stack canaries and address space layout randomization.
The vulnerability demonstrates a clear violation of the principle of least privilege and proper resource initialization in kernel code. According to ATT&CK framework category T1068, which covers "Local Privilege Escalation," this vulnerability could potentially be leveraged as a stepping stone for privilege escalation attacks. The information disclosure aspect of this vulnerability also aligns with T1005, which covers "Data from Local System," and T1082, which addresses "System Information Discovery." Organizations should consider this vulnerability as part of their comprehensive vulnerability management strategy, particularly when assessing systems that may be running older kernel versions or when implementing security controls for amateur radio or specialized networking environments. The fix for this vulnerability required proper initialization of the affected data structure in the kernel source code, which was implemented in kernel version 3.9-rc7 and subsequent stable releases.
Mitigation strategies for this vulnerability primarily involve upgrading to a patched kernel version, which is the most effective solution. System administrators should prioritize patching affected systems, particularly those running kernel versions prior to 3.9-rc7. In environments where immediate upgrading is not feasible, organizations can implement additional security controls such as restricting local user access to systems running vulnerable kernel versions, monitoring for suspicious recvmsg or recvfrom system call patterns, and implementing network segmentation to limit potential attack vectors. The vulnerability also underscores the importance of thorough code reviews and security testing of kernel modules, particularly focusing on proper initialization of all data structures before use. Security teams should also consider implementing runtime monitoring solutions that can detect and alert on unusual system call patterns that might indicate exploitation attempts. Additionally, organizations should maintain current knowledge of kernel security advisories and implement automated patch management processes to ensure timely deployment of security fixes across their infrastructure.