CVE-1999-0804 in Linux
Summary
by MITRE
Denial of service in Linux 2.2.x kernels via malformed ICMP packets containing unusual types, codes, and IP header lengths.
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Analysis
by VulDB Data Team • 09/17/2024
The vulnerability described in CVE-1999-0804 represents a critical denial of service weakness affecting Linux 2.2.x kernel versions through improper handling of malformed Internet Control Message Protocol packets. This issue stems from the kernel's insufficient validation mechanisms when processing ICMP packets that contain unusual combinations of packet types, codes, and IP header lengths. The flaw exists in the kernel's network stack implementation where incoming ICMP packets are not adequately sanitized before processing, creating a pathway for malicious actors to exploit the system's response handling routines.
The technical implementation of this vulnerability resides in the kernel's ICMP packet processing subsystem where the code fails to properly validate the structure and content of incoming packets. When the kernel receives an ICMP packet with malformed characteristics including non-standard types, unexpected codes, or irregular IP header lengths, the processing logic encounters undefined behavior that can lead to system crashes or complete system hangs. This occurs because the kernel's packet validation routines do not account for all possible combinations of packet attributes that could be transmitted over the network, particularly in edge cases involving malformed IP headers.
The operational impact of this vulnerability extends beyond simple service disruption as it can result in complete system compromise through sustained denial of service attacks. Attackers can exploit this weakness by crafting specific ICMP packets that trigger the kernel's handling routines to enter infinite loops, memory corruption states, or other error conditions that cause the system to become unresponsive. The vulnerability affects systems running Linux 2.2.x kernels where the network stack has not been patched or updated to include proper validation of ICMP packet structures. This makes the issue particularly dangerous for network infrastructure devices, servers, and any system where continuous availability is critical.
Mitigation strategies for CVE-1999-0804 require immediate kernel updates to versions that include proper ICMP packet validation and input sanitization routines. System administrators should prioritize patching affected Linux 2.2.x systems with kernel versions that address this specific vulnerability in the network stack processing. Network-level protections can include implementing firewall rules to filter suspicious ICMP traffic or employing intrusion detection systems that can identify and block malformed ICMP packets before they reach the kernel processing layer. Additionally, monitoring systems should be configured to detect unusual network behavior patterns that may indicate exploitation attempts. From a cybersecurity perspective, this vulnerability aligns with CWE-129, which addresses validation of input boundaries, and maps to ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing network segmentation strategies to limit the potential impact of such attacks and establish robust incident response procedures to address potential exploitation attempts.