CVE-2019-9003 in Linux
Summary
by MITRE
In the Linux kernel before 4.20.5, attackers can trigger a drivers/char/ipmi/ipmi_msghandler.c use-after-free and OOPS by arranging for certain simultaneous execution of the code, as demonstrated by a "service ipmievd restart" loop.
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Analysis
by VulDB Data Team • 07/19/2023
The vulnerability identified as CVE-2019-9003 represents a critical use-after-free condition within the Linux kernel's IPMI message handler component. This flaw exists in kernel versions prior to 4.20.5 and specifically affects the drivers/char/ipmi/ipmi_msghandler.c file where improper memory management allows for potential exploitation. The issue manifests when specific concurrent execution scenarios occur during the handling of IPMI (Intelligent Platform Management Interface) messages, creating a scenario where freed memory locations are accessed after deallocation, leading to system instability and potential privilege escalation.
The technical implementation of this vulnerability involves the manipulation of IPMI message processing functions that handle asynchronous communication between management controllers and the system. When the ipmievd service restarts in a loop, it creates a race condition scenario where multiple threads attempt to access the same memory structures simultaneously. The use-after-free occurs because the kernel does not properly validate that memory regions remain allocated before accessing them, allowing attackers to potentially corrupt memory or execute arbitrary code. This condition can be triggered through legitimate system operations but becomes exploitable when combined with specific timing and concurrent access patterns. The vulnerability directly maps to CWE-416 which describes the use of freed memory condition, and aligns with ATT&CK technique T1068 which covers exploitation of remote services.
The operational impact of CVE-2019-9003 extends beyond simple system crashes to potentially enable privilege escalation and persistent access to affected systems. An attacker who successfully exploits this vulnerability can cause the kernel to panic and generate an OOPS message, which represents a kernel-level error that typically results in system instability or complete system crash. In more sophisticated exploitation scenarios, the use-after-free condition could be leveraged to execute arbitrary code with kernel privileges, potentially allowing attackers to bypass security controls and establish persistent backdoors. The vulnerability affects systems running Linux kernel versions 4.19 and earlier, making it particularly concerning for enterprise environments where kernel updates may be delayed or where legacy systems remain operational. The specific trigger involving ipmievd service restarts suggests that this vulnerability is particularly relevant in data center environments where IPMI management is actively used for system monitoring and remote management purposes.
Mitigation strategies for CVE-2019-9003 primarily focus on kernel version updates to 4.20.5 or later, which contain the necessary patches to address the memory management issues in the IPMI message handler. Organizations should prioritize patching affected systems and implementing proper kernel update policies to prevent exploitation. Additionally, system administrators should consider disabling IPMI services when not actively required for management purposes, as this reduces the attack surface and limits potential exploitation vectors. Monitoring for suspicious ipmievd restart patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability also highlights the importance of proper memory management practices in kernel space code and underscores the need for comprehensive security testing of system drivers, particularly those handling asynchronous communication protocols. Network segmentation and access control measures should be implemented to limit potential attackers' ability to interact with IPMI interfaces, as this vulnerability requires some level of system interaction to exploit effectively.