CVE-2007-3848 in Linux
Summary
by MITRE
Linux kernel 2.4.35 and other versions allows local users to send arbitrary signals to a child process that is running at higher privileges by causing a setuid-root parent process to die, which delivers an attacker-controlled parent process death signal (PR_SET_PDEATHSIG).
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Analysis
by VulDB Data Team • 07/25/2019
This vulnerability exists in the linux kernel version 2.4.35 and earlier releases where a local attacker can exploit a flaw in the process death signal mechanism to send arbitrary signals to privileged child processes. The vulnerability specifically relates to the pr_set_pdeathsig system call which allows a parent process to set a signal that will be sent to its child when the parent dies. When a setuid-root parent process terminates, it can deliver a signal to its child processes that may be running with elevated privileges, creating a potential privilege escalation vector.
The technical flaw stems from the improper handling of process death signals in the kernel's process management subsystem. When a parent process with elevated privileges dies, the kernel does not properly validate or sanitize the signal that is to be delivered to child processes. This allows an attacker to manipulate the parent process in such a way that it terminates with a signal that the attacker controls, thereby enabling the execution of arbitrary signals against child processes that maintain their elevated privileges. The vulnerability is particularly dangerous because it can be exploited even when the child process is running with root privileges, potentially allowing local users to escalate their privileges.
The operational impact of this vulnerability is significant as it enables local privilege escalation attacks that can be executed by any user with access to the system. Attackers can exploit this vulnerability to gain root access by manipulating the death signal of a setuid-root parent process to deliver signals that can be used to escalate privileges or execute malicious code with elevated privileges. This creates a persistent threat that can be leveraged for further attacks within the system. The vulnerability affects systems running kernel versions 2.4.35 and earlier, making it a critical concern for organizations still operating legacy systems.
Mitigation strategies for this vulnerability include upgrading to kernel versions 2.6.22 or later where the vulnerability has been patched, implementing proper process management controls, and ensuring that setuid programs are carefully reviewed for potential security implications. System administrators should also consider implementing additional security controls such as mandatory access controls, process monitoring, and regular security audits to detect and prevent exploitation attempts. This vulnerability aligns with CWE-284 Access Control and ATT&CK techniques related to privilege escalation and process manipulation, highlighting the need for comprehensive security measures in kernel-level process management.
The vulnerability demonstrates the importance of proper signal handling in kernel space and the potential consequences of inadequate privilege separation. It underscores the need for robust process management mechanisms that prevent uncontrolled signal delivery between processes with different privilege levels. Organizations should implement regular kernel updates and security assessments to address similar vulnerabilities that may exist in their systems. The fix for this vulnerability involved strengthening the validation of process death signals and ensuring that only appropriate signals are delivered to child processes when their parents terminate.