CVE-2007-4774 in Linux
Summary
by MITRE
The Linux kernel before 2.4.36-rc1 has a race condition. It was possible to bypass systrace policies by flooding the ptraced process with SIGCONT signals, which can can wake up a PTRACED process.
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Analysis
by VulDB Data Team • 04/21/2023
The vulnerability identified as CVE-2007-4774 represents a critical race condition within the Linux kernel version 2.4.36-rc1 and earlier, affecting systems that utilize systrace security policies. This flaw resides in the kernel's handling of process tracing mechanisms, specifically involving the ptrace system call which allows one process to observe and control another process's execution. The vulnerability manifests when a malicious actor attempts to circumvent systrace policies by exploiting a timing window in the kernel's process tracing implementation.
The technical flaw occurs due to improper synchronization between the ptrace system call and signal handling mechanisms within the kernel. When a process is being traced, the kernel maintains specific state information to enforce security policies. However, in the affected kernel versions, a race condition exists between the process tracing state management and signal delivery. An attacker can exploit this by rapidly sending SIGCONT signals to a ptraced process, effectively disrupting the normal execution flow and potentially allowing unauthorized operations to bypass the systrace policy enforcement mechanisms.
This race condition creates a significant operational impact as it undermines the fundamental security model of systrace, which is designed to restrict system call execution based on predefined policies. The vulnerability allows for privilege escalation and arbitrary code execution in scenarios where systrace is properly configured to limit process behavior. Attackers can leverage this flaw to bypass security controls that would normally prevent certain system calls or file operations, effectively rendering the systrace security framework ineffective. The exploitation requires the attacker to have some level of access to the target process but does not require elevated privileges, making it particularly dangerous in multi-user environments.
The vulnerability aligns with CWE-362, which identifies race conditions as a common security weakness where concurrent operations can lead to unexpected behavior. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and process injection methods, as it enables bypassing security controls that would normally prevent unauthorized process manipulation. The attack vector specifically relates to T1055, which covers process injection techniques, and T1068, which addresses privilege escalation through local exploitation.
Mitigation strategies for CVE-2007-4774 require immediate kernel updates to version 2.4.36-rc1 or later, where the race condition has been resolved through proper synchronization mechanisms. System administrators should also review and audit existing systrace configurations to ensure that alternative security measures are implemented where necessary. The fix implemented in the updated kernel versions addresses the core synchronization issue by ensuring that ptrace state changes are properly protected against concurrent signal delivery, preventing the race condition that enabled policy bypass. Organizations should also consider implementing additional monitoring and alerting mechanisms to detect unusual signal activity patterns that might indicate exploitation attempts.