Source: cve@mitre.org
The (1) ipq_read and (2) ipulog_read functions in iptables allow local users to cause a denial of service by sending spoofed messages as other users to the kernel netlink interface.
Local users can exploit a vulnerability in iptables to cause a denial-of-service (DoS) condition by sending crafted messages via the kernel netlink interface. This allows an attacker to disrupt network traffic and potentially impact critical services by leveraging spoofed messages to exhaust system resources. The vulnerability stems from improper handling of user-supplied data within the ipq_read and ipulog_read functions.
Step 1: User Access: An attacker gains local access to the target system, potentially through compromised credentials or other local vulnerabilities.
Step 2: Spoofed Message Creation: The attacker crafts a malicious netlink message, spoofing the identity of another user. This message is designed to trigger a specific behavior within the ipq_read or ipulog_read functions.
Step 3: Message Injection: The attacker uses a tool or script to inject the crafted netlink message into the kernel netlink interface, targeting the iptables subsystem.
Step 4: Function Execution: The ipq_read or ipulog_read function receives the spoofed message. Due to the lack of proper validation, the function processes the message as if it originated from the legitimate user.
Step 5: Resource Exhaustion: The malicious message exploits a flaw in the function's logic, potentially leading to resource exhaustion (e.g., excessive memory allocation, CPU usage) or other disruptive behavior.
Step 6: Denial of Service: The resource exhaustion or disruptive behavior results in a denial-of-service condition, impacting network traffic or other critical services.
The vulnerability lies within the ipq_read and ipulog_read functions of iptables, specifically in how they handle messages received through the kernel netlink interface. The functions fail to properly validate the source of the messages, allowing a local user to craft and send spoofed messages that appear to originate from other users. This lack of proper input validation and authorization allows an attacker to potentially exhaust kernel resources, leading to a DoS. The root cause is a flaw in the access control mechanism, where the functions do not adequately verify the identity or permissions of the sending user before processing the netlink messages. This allows an attacker to bypass intended access controls and manipulate the iptables functionality.
While no specific APTs are directly linked to this CVE, the techniques used (spoofing, exploiting kernel interfaces) are common in various attack campaigns. The vulnerability itself is not listed on the CISA KEV catalog due to its age and the availability of patches. However, the underlying principles are relevant to modern attacks. Attackers could potentially use this vulnerability as part of a larger attack chain to achieve a more significant impact.
Monitor system logs for unusual activity related to iptables and the netlink interface.
Analyze network traffic for suspicious netlink messages, especially those originating from local users.
Examine system resource usage (CPU, memory) for spikes that coincide with iptables activity.
Implement intrusion detection rules to identify crafted netlink messages based on known exploit patterns.
Monitor for iptables rule modifications that are not authorized.
Apply the security patches provided by the Linux distribution vendor.
Implement strict input validation for all data received through the netlink interface.
Enforce proper access control and authorization mechanisms for netlink messages.
Regularly update iptables and related packages to the latest versions.
Implement a defense-in-depth strategy, including firewalls, intrusion detection systems, and regular security audits.
Consider using a more secure firewall management tool if available.