CVE-2008-0028 in PIX
Summary
by MITRE
Unspecified vulnerability in Cisco PIX 500 Series Security Appliance and 5500 Series Adaptive Security Appliance (ASA) before 7.2(3)6 and 8.0(3), when the Time-to-Live (TTL) decrement feature is enabled, allows remote attackers to cause a denial of service (device reload) via a crafted IP packet.
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Analysis
by VulDB Data Team • 08/04/2019
The vulnerability identified as CVE-2008-0028 represents a critical denial of service flaw affecting Cisco PIX 500 Series Security Appliances and ASA 5500 Series Adaptive Security Appliances. This weakness specifically manifests when the Time-to-Live decrement feature is activated, creating a condition where maliciously crafted IP packets can trigger device instability. The vulnerability operates at the network layer, exploiting fundamental packet processing mechanisms within the firewall's routing and packet inspection capabilities. Security professionals should recognize this as a significant threat to network availability, particularly in environments where these appliances serve as primary security gateways.
The technical implementation of this vulnerability stems from improper handling of IP packet TTL values during the packet processing cycle. When the TTL decrement feature is enabled, the security appliance performs automatic decrementing of the Time-to-Live field as packets traverse the device. However, the flaw occurs when malformed or specially crafted IP packets are received with specific TTL values that cause integer underflow conditions or buffer manipulation within the device's packet processing engine. This condition leads to memory corruption or unexpected state changes that ultimately result in the appliance performing an automatic restart or reload operation. The vulnerability aligns with CWE-129, which addresses improper validation of length values, and CWE-191, concerning integer underflow conditions that can lead to memory corruption.
The operational impact of this vulnerability extends beyond simple service disruption, as it can result in complete network availability loss for organizations relying on affected Cisco appliances. Attackers can exploit this weakness remotely without requiring authentication credentials, making it particularly dangerous in perimeter security deployments. The device reload operation typically results in temporary network outages that can last from several minutes to hours depending on the appliance configuration and network recovery procedures. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1499, specifically targeting network denial of service conditions. Organizations with critical network infrastructure depending on these appliances face significant operational risks, particularly in mission-critical environments where network availability is paramount.
Mitigation strategies for this vulnerability require immediate implementation of firmware updates to versions 7.2(3)6 or 8.0(3) and later, which contain the necessary patches to address the TTL decrement handling flaw. Network administrators should also consider implementing temporary network segmentation or access controls to limit exposure while applying patches. Additional protective measures include monitoring network traffic for unusual TTL values and implementing intrusion detection systems that can identify potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and state management in network security devices, as highlighted in industry best practices for secure network appliance development. Organizations should also review their incident response procedures to ensure rapid deployment of patches and recovery protocols when similar vulnerabilities are discovered in their security infrastructure.