CVE-2007-1592 in Linux
Summary
by MITRE
net/ipv6/tcp_ipv6.c in Linux kernel 2.6.x up to 2.6.21-rc3 inadvertently copies the ipv6_fl_socklist from a listening TCP socket to child sockets, which allows local users to cause a denial of service (OOPS) or double free by opening a listening IPv6 socket, attaching a flow label, and connecting to that socket.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability described in CVE-2007-1592 represents a critical flaw in the Linux kernel's IPv6 implementation that affects versions 2.6.x up to 2.6.21-rc3. This issue stems from improper memory management within the tcp_ipv6.c file where the kernel fails to properly handle the ipv6_fl_socklist structure during socket inheritance. The flaw occurs when a listening TCP socket is created with a flow label attached, and subsequent child sockets inherit this flow label structure without proper initialization or validation mechanisms.
The technical execution of this vulnerability involves a specific sequence of operations that exploits the kernel's socket creation and inheritance mechanisms. When a local user creates a listening IPv6 socket and attaches a flow label to it, the kernel stores this flow label information in the ipv6_fl_socklist structure. During subsequent connection attempts, child sockets inherit this structure but the kernel does not properly validate or manage the flow label references, leading to potential memory corruption scenarios. This improper inheritance creates a situation where the same memory location can be freed multiple times or accessed after deallocation, resulting in system instability.
The operational impact of this vulnerability manifests as either a denial of service condition through kernel OOPS (Oops error) or more severe double free conditions that can potentially lead to system crashes or memory corruption. The OOPS condition occurs when the kernel attempts to access invalid memory locations due to improper flow label handling, while the double free scenario happens when the same memory block is deallocated twice during the socket lifecycle. Both conditions can be triggered by local users with minimal privileges, making this a particularly concerning vulnerability as it does not require network access or elevated permissions to exploit.
This vulnerability maps to CWE-415 Double Free and CWE-416 Use After Free within the Common Weakness Enumeration framework, demonstrating the kernel's failure to properly manage memory resources during socket inheritance operations. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under T1068, which covers Exploitation for Privilege Escalation, though in this case the exploitation is limited to local privilege escalation and denial of service rather than remote code execution. The vulnerability highlights the importance of proper resource management in kernel space programming and demonstrates how seemingly minor memory management issues can lead to significant system instability.
The recommended mitigations for this vulnerability include immediate patching of affected kernel versions to the stable releases that contain the fix for improper socket flow label handling. System administrators should prioritize updating their Linux systems to versions beyond 2.6.21-rc3 where this memory management issue has been resolved. Additionally, monitoring systems should be implemented to detect unusual memory allocation patterns or kernel OOPS messages that might indicate exploitation attempts. Organizations should also consider implementing kernel hardening measures such as stack canaries and address space layout randomization to further reduce the impact of potential exploitation attempts. The fix typically involves proper validation of socket inheritance mechanisms and ensuring that flow label structures are correctly managed during socket creation and destruction phases.