CVE-2016-7039 in Linux
Summary
by MITRE • 01/25/2023
The IP stack in the Linux kernel through 4.8.2 allows remote attackers to cause a denial of service (stack consumption and panic) or possibly have unspecified other impact by triggering use of the GRO path for large crafted packets, as demonstrated by packets that contain only VLAN headers, a related issue to CVE-2016-8666.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2016-7039 represents a critical flaw in the Linux kernel's network stack implementation that affects versions through 4.8.2. This issue specifically targets the Generic Receive Offload (GRO) functionality, which is designed to improve network performance by aggregating multiple small packets into larger ones before processing. The vulnerability arises when the kernel encounters specially crafted large packets that trigger the GRO path in an unexpected manner, leading to potential system instability and denial of service conditions.
The technical exploitation of this vulnerability occurs through the manipulation of packet processing within the network stack's GRO mechanism. Attackers can craft packets that contain only VLAN headers, which when processed through the GRO path cause excessive stack consumption and ultimately lead to system panics. This flaw operates at the kernel level, specifically within the network protocol implementation where the kernel's packet handling routines fail to properly validate packet sizes and structures when processing GRO operations. The vulnerability is particularly concerning because it can be triggered remotely without requiring authentication or special privileges, making it an attractive target for automated attacks.
The operational impact of CVE-2016-7039 extends beyond simple denial of service conditions to potentially compromise entire network infrastructure. Systems running affected kernel versions become vulnerable to stack exhaustion attacks that can cause kernel panics and system crashes, effectively rendering network services unavailable. This vulnerability is classified under CWE-129 as an Improper Validation of Array Index, as the kernel fails to properly validate the size and structure of packets before processing them through GRO operations. The attack vector aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries leverage system weaknesses to disrupt network communications.
Network administrators and system operators face significant challenges when addressing this vulnerability due to its potential for widespread impact across various network environments. The flaw affects systems that process network traffic through the GRO mechanism, which is enabled by default on most modern Linux distributions, making the attack surface particularly broad. The vulnerability's relationship to CVE-2016-8666 demonstrates a pattern of similar issues within the kernel's network stack implementation, suggesting deeper architectural problems with packet validation and resource management. Organizations must prioritize patching efforts and implement network segmentation strategies to mitigate exposure, while also monitoring for signs of exploitation attempts that may manifest as unusual network traffic patterns or system instability.
Mitigation strategies for CVE-2016-7039 should include immediate kernel updates to versions that contain the necessary patches, as well as network-level controls to filter out suspicious packet patterns. System administrators should consider disabling GRO functionality on affected systems as a temporary workaround while patches are deployed, though this may impact network performance. The vulnerability highlights the importance of robust input validation and resource management in kernel space operations, emphasizing the need for comprehensive testing of network stack components against various packet structures and sizes. Additionally, implementing intrusion detection systems that can identify anomalous packet patterns consistent with this vulnerability can provide early warning capabilities for potential exploitation attempts.