CVE-2005-2873 in Linux
Summary
by MITRE
the ipt_recent kernel module (ipt_recent.c) in linux kernel 2.6.12 and earlier does not properly perform certain time tests when the jiffies value is greater than long_max which can cause ipt_recent netfilter rules to block too early a different vulnerability than cve-2005-2872.
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Analysis
by VulDB Data Team • 07/15/2019
The ipt_recent kernel module represents a critical security vulnerability in Linux kernel versions 2.6.12 and earlier, specifically addressing improper time testing mechanisms that can lead to premature rule enforcement. This flaw resides within the netfilter framework's packet filtering capabilities, where the module maintains lists of recently seen IP addresses to enforce rate limiting and access control policies. The vulnerability stems from the module's failure to correctly handle time calculations when the jiffies counter exceeds the maximum value that can be represented by a long integer type, creating a scenario where network access controls malfunction due to integer overflow conditions.
The technical implementation of this vulnerability involves the ipt_recent module's reliance on the kernel's jiffies counter for tracking time intervals between packet arrivals from the same IP address. When jiffies values approach or exceed LONG_MAX, the time comparison logic fails because the module cannot properly perform arithmetic operations on time values that exceed the maximum representable long integer. This condition creates a race where legitimate traffic may be incorrectly blocked before the configured time thresholds have been reached, effectively disabling the intended rate limiting functionality. The flaw operates as a time-based logic error rather than a traditional buffer overflow or memory corruption issue.
The operational impact of this vulnerability extends beyond simple access denial, as it fundamentally undermines the integrity of network access control policies implemented through iptables rules. Attackers could potentially exploit this condition to bypass rate limiting controls or cause legitimate network traffic to be incorrectly blocked, leading to service disruption and potential denial of service conditions. The vulnerability affects systems running kernel versions up to and including 2.6.12, making it particularly concerning for legacy systems that have not been updated to newer kernel releases. Network administrators relying on ipt_recent for security policy enforcement would experience unexpected behavior where access controls fail to function according to their intended parameters.
Mitigation strategies for this vulnerability require immediate kernel updates to versions that address the jiffies overflow handling in the ipt_recent module, typically found in kernel versions 2.6.13 and later. System administrators should also review and validate existing iptables rules that utilize the recent module to ensure proper configuration of time thresholds and maximum connection limits. The vulnerability aligns with CWE-191, which describes integer underflow or overflow conditions, and can be mapped to ATT&CK technique T1562.007 for "Timestomp' and T1071.004 for 'Application Layer Protocol: DNS' in scenarios where network access controls fail due to time-based logic errors. Organizations should implement monitoring to detect unusual traffic patterns that might indicate the vulnerability's exploitation and maintain updated security policies to address the underlying integer overflow condition in kernel space.