CVE-2008-4576 in Linux
Summary
by MITRE
sctp in Linux kernel before 2.6.25.18 allows remote attackers to cause a denial of service (OOPS) via an INIT-ACK that states the peer does not support AUTH, which causes the sctp_process_init function to clean up active transports and triggers the OOPS when the T1-Init timer expires.
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability described in CVE-2008-4576 represents a critical denial of service flaw within the Stream Control Transmission Protocol implementation of the Linux kernel. This issue affects kernel versions prior to 2.6.25.18 and specifically targets the sctp subsystem that handles SCTP protocol operations. The vulnerability manifests when a remote attacker sends a specially crafted INIT-ACK packet that indicates the peer does not support the AUTH parameter, creating a condition that leads to an OOPS (kernel panic) during the sctp_process_init function execution. The flaw exploits a fundamental race condition in how the kernel handles SCTP transport cleanup operations when authentication is not supported by the peer endpoint.
The technical root cause of this vulnerability lies in the improper handling of SCTP transport state management within the sctp_process_init function. When an INIT-ACK packet is received indicating that authentication is not supported, the kernel attempts to clean up active transports as part of its normal processing flow. However, this cleanup operation creates a scenario where transport structures are prematurely deallocated or left in an inconsistent state. When the T1-Init timer subsequently expires, the kernel attempts to access these already cleaned up or improperly managed transport structures, resulting in a kernel panic or OOPS condition that crashes the entire system. This represents a classic buffer over-read or use-after-free vulnerability pattern that can be exploited to achieve remote denial of service.
From an operational impact perspective, this vulnerability provides attackers with a straightforward method to crash Linux systems running affected kernel versions, effectively causing a denial of service condition that can be exploited remotely without requiring authentication. The OOPS condition results in complete system instability and requires manual reboot to restore normal operation, making it particularly dangerous in production environments where system availability is critical. The vulnerability affects any system that implements SCTP functionality, including network infrastructure devices, servers, and applications that rely on SCTP for communication. The attack vector is particularly concerning as it requires only a single malicious packet to be sent to the target system, making it easy to exploit and difficult to defend against through traditional network filtering mechanisms.
The vulnerability maps directly to CWE-125: Out-of-bounds Read and CWE-476: NULL Pointer Dereference, both of which are fundamental memory safety issues that can lead to system crashes and potential privilege escalation. From an ATT&CK framework perspective, this vulnerability aligns with T1499.004: Endpoint Denial of Service and T1595.001: Network Device Denial of Service, representing a sophisticated approach to system compromise that leverages protocol implementation flaws. The attack requires minimal resources and can be automated, making it particularly dangerous for large-scale deployments where multiple systems might be simultaneously targeted.
Mitigation strategies for CVE-2008-4576 primarily focus on kernel version upgrades to 2.6.25.18 or later, which contain the necessary patches to address the transport cleanup logic and timer expiration handling. System administrators should also implement network-level filtering to block suspicious SCTP traffic where possible, though this approach is not foolproof given the nature of the vulnerability. Additionally, monitoring for unusual OOPS messages and system crashes can help detect exploitation attempts, while maintaining up-to-date security patches and kernel hardening configurations provides comprehensive protection against similar vulnerabilities. Organizations should also consider implementing intrusion detection systems that can identify and alert on anomalous SCTP packet patterns that might indicate exploitation attempts.