CVE-2006-1527 in Linux
Summary
by MITRE
The SCTP-netfilter code in Linux kernel before 2.6.16.13 allows remote attackers to trigger a denial of service (infinite loop) via unknown vectors that cause an invalid SCTP chunk size to be processed by the for_each_sctp_chunk function.
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Analysis
by VulDB Data Team • 03/13/2021
The vulnerability identified as CVE-2006-1527 resides within the SCTP-netfilter implementation of the Linux kernel, specifically affecting versions prior to 2.6.16.13. This issue represents a critical flaw in the kernel's handling of Stream Control Transmission Protocol chunks, which are essential components for managing data transmission in network communications. The vulnerability manifests when the kernel processes SCTP chunks with invalid size parameters, creating a condition that can be exploited by remote attackers to disrupt system operations. The affected code path involves the for_each_sctp_chunk function, which is responsible for iterating through SCTP chunks within network packets. When malformed chunk sizes are encountered, this iteration mechanism becomes trapped in an infinite loop, consuming system resources and rendering the affected system unavailable to legitimate users.
The technical exploitation of this vulnerability occurs through the manipulation of SCTP packet structures, specifically by crafting packets with invalid chunk size fields that cause the kernel's SCTP processing code to enter an infinite loop during chunk iteration. This condition is classified under CWE-835, which deals with infinite loops in software systems. The flaw is particularly dangerous because it can be triggered remotely without requiring authentication or special privileges, making it an attractive target for denial of service attacks. The for_each_sctp_chunk function, which employs a macro-based iteration approach, fails to properly validate chunk size parameters before processing, leading to the loop condition where the iteration continues indefinitely. This behavior is consistent with the ATT&CK technique T1499.004, which covers network denial of service attacks targeting system resources.
The operational impact of this vulnerability extends beyond simple service disruption, as the infinite loop consumes CPU cycles and memory resources, potentially leading to system instability or complete system crashes. The vulnerability affects systems running Linux kernels with SCTP support and netfilter integration, making it particularly relevant for servers and network infrastructure components that handle SCTP traffic. The attack surface is broad since SCTP is used in various network applications including telecommunications signaling protocols, multimedia streaming, and other real-time communication systems. Organizations relying on Linux-based systems for critical network services face significant risk from this vulnerability, as attackers can easily exploit it to create persistent denial of service conditions. The vulnerability's remote exploitability means that attackers can target systems from anywhere on the network, making it difficult to defend against through traditional network segmentation approaches.
Mitigation strategies for CVE-2006-1527 primarily focus on kernel version updates, with the most effective solution being the upgrade to Linux kernel version 2.6.16.13 or later, where the vulnerability has been patched. System administrators should also implement network-level filtering to block SCTP traffic when it is not required for specific services, reducing the attack surface. The patch for this vulnerability addresses the improper validation of SCTP chunk sizes within the for_each_sctp_chunk function, ensuring that invalid chunk sizes are properly handled to prevent infinite loop conditions. Additionally, monitoring systems should be configured to detect unusual CPU utilization patterns that might indicate exploitation attempts, as the infinite loop will manifest as sustained high CPU usage. Organizations should also consider implementing intrusion detection systems that can identify malformed SCTP packets and alert administrators to potential exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space code and demonstrates how seemingly minor validation flaws can lead to significant security implications.