CVE-2013-4470 in Linux
Summary
by MITRE
The Linux kernel before 3.12, when UDP Fragmentation Offload (UFO) is enabled, does not properly initialize certain data structures, which allows local users to cause a denial of service (memory corruption and system crash) or possibly gain privileges via a crafted application that uses the UDP_CORK option in a setsockopt system call and sends both short and long packets, related to the ip_ufo_append_data function in net/ipv4/ip_output.c and the ip6_ufo_append_data function in net/ipv6/ip6_output.c.
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Analysis
by VulDB Data Team • 06/01/2021
The vulnerability identified as CVE-2013-4470 represents a critical flaw in the Linux kernel's handling of UDP Fragmentation Offload functionality, specifically affecting kernel versions prior to 3.12. This issue arises from improper initialization of data structures within the network stack when UFO is enabled, creating a pathway for malicious exploitation that can result in either system crashes or privilege escalation. The vulnerability manifests through the manipulation of UDP_CORK socket options in conjunction with the transmission of both short and long packets, exploiting fundamental flaws in how the kernel manages fragmented network data.
The technical root cause of this vulnerability lies in the ip_ufo_append_data function located in net/ipv4/ip_output.c and the ip6_ufo_append_data function in net/ipv6/ip6_output.c. These functions fail to properly initialize memory structures when processing UDP packets that utilize the UFO feature, which is designed to offload packet fragmentation to network hardware rather than handling it in software. When a malicious application leverages the UDP_CORK option alongside mixed packet sizes, the kernel's memory management routines become corrupted, leading to unpredictable behavior. This flaw falls under CWE-129, representing an insufficient bounds checking vulnerability that allows for memory corruption through improper initialization of data structures.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable privilege escalation, making it particularly dangerous in multi-user environments or systems where untrusted applications might be executed. Local attackers can exploit this vulnerability by crafting specific network traffic patterns that trigger the corrupted memory handling paths, causing kernel memory corruption that results in system crashes or potentially allowing for arbitrary code execution with kernel privileges. The vulnerability demonstrates the classic attack pattern described in the ATT&CK framework under T1068, where local privilege escalation is achieved through exploitation of kernel-level flaws. Systems running affected kernel versions are susceptible to both immediate system instability and potential long-term security compromise.
Mitigation strategies for CVE-2013-4470 primarily involve upgrading to kernel versions 3.12 or later where the vulnerability has been addressed through proper initialization of data structures in the UFO handling functions. System administrators should also consider disabling UDP Fragmentation Offload functionality if it is not required for network performance optimization, which can be accomplished through kernel parameter modifications or network interface configuration changes. Additionally, monitoring network traffic for unusual patterns involving UDP_CORK usage and mixed packet sizes can help detect potential exploitation attempts. The fix implemented in kernel 3.12 specifically addresses the memory initialization issues in both IPv4 and IPv6 UFO append data functions, ensuring proper allocation and handling of network buffer structures. Organizations should also implement comprehensive patch management processes to ensure all systems receive timely kernel updates, as this vulnerability represents a persistent risk in older kernel versions and could be exploited by sophisticated attackers seeking to establish persistent access to target systems.