CVE-2017-5986 in Linux
Summary
by MITRE
Race condition in the sctp_wait_for_sndbuf function in net/sctp/socket.c in the Linux kernel before 4.9.11 allows local users to cause a denial of service (assertion failure and panic) via a multithreaded application that peels off an association in a certain buffer-full state.
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Analysis
by VulDB Data Team • 08/16/2020
The vulnerability identified as CVE-2017-5986 represents a critical race condition affecting the Stream Control Transmission Protocol implementation within the Linux kernel. This flaw exists in the sctp_wait_for_sndbuf function located in net/sctp/socket.c and impacts kernel versions prior to 4.9.11. The issue manifests when a multithreaded application attempts to peel off an association while the send buffer is in a specific full state, creating a scenario where concurrent operations can lead to system instability.
The technical root cause of this vulnerability stems from improper synchronization mechanisms within the SCTP socket implementation. When multiple threads attempt to access and modify the send buffer state simultaneously, the race condition allows for inconsistent buffer management. The sctp_wait_for_sndbuf function fails to properly handle concurrent access patterns, leading to assertion failures that ultimately result in kernel panics. This occurs because the function does not adequately protect against simultaneous buffer state modifications from different threads, causing the kernel to detect an internal inconsistency that triggers a hard system crash.
The operational impact of this vulnerability extends beyond simple denial of service, as it can lead to complete system crashes and potential data loss. Local attackers with access to the system can exploit this condition by crafting specific multithreaded applications that manipulate SCTP associations in the buffer-full state. The vulnerability is particularly dangerous because it can be triggered through normal application behavior rather than requiring malicious code execution, making it a significant threat to systems relying on SCTP for communication. Systems utilizing SCTP for applications such as telephony signaling, financial transactions, or real-time communications are particularly at risk.
Mitigation strategies for CVE-2017-5986 primarily focus on kernel version updates, with the most effective solution being the deployment of Linux kernel versions 4.9.11 or later where the race condition has been addressed through improved synchronization mechanisms. Organizations should also implement monitoring systems to detect unusual SCTP behavior patterns that might indicate exploitation attempts. Additionally, security teams should consider disabling SCTP functionality when it is not required for system operations, reducing the attack surface. The vulnerability aligns with CWE-362, which specifically addresses race conditions in concurrent programming, and represents a classic example of how improper synchronization can lead to system instability. From an ATT&CK framework perspective, this vulnerability could be categorized under privilege escalation and denial of service tactics, as it allows local users to cause system-wide disruptions through carefully crafted concurrent operations.