CVE-2008-1159 in IOS
Summary
by MITRE
Multiple unspecified vulnerabilities in the SSH server in Cisco IOS 12.4 allow remote attackers to cause a denial of service (device restart) via unknown vectors, aka Bug ID (1) CSCsk42419, (2) CSCsk60020, and (3) CSCsh51293.
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Analysis
by VulDB Data Team • 06/01/2025
The vulnerability identified as CVE-2008-1159 represents a critical security flaw in Cisco IOS 12.4 SSH server implementations that enables remote attackers to execute denial of service attacks resulting in complete device restarts. This vulnerability affects multiple Cisco IOS versions and manifests through unspecified attack vectors that exploit weaknesses in the Secure Shell protocol implementation within the network operating system. The issue was documented under multiple bug IDs including CSCsk42419, CSCsk60020, and CSCsh51293, indicating the complexity and severity of the underlying flaws that impact the SSH service functionality.
The technical nature of this vulnerability stems from insufficient input validation and error handling mechanisms within the SSH server component of Cisco IOS 12.4. When remote attackers send malformed or specially crafted SSH protocol requests, the system fails to properly process these inputs and instead crashes or restarts the device entirely. This behavior aligns with CWE-129, Input Validation, and CWE-248, Uncaught Exception, as the system does not properly validate incoming SSH protocol data or handle exceptional conditions during protocol processing. The flaw demonstrates characteristics of a buffer overflow condition or improper state handling that leads to system instability and complete service disruption.
The operational impact of CVE-2008-1159 extends beyond simple service interruption to potentially compromise network infrastructure reliability and availability. Network administrators face the risk of unauthorized parties deliberately targeting critical network devices such as routers and switches running affected Cisco IOS versions. The remote exploitation capability means that attackers can initiate denial of service attacks from anywhere on the network without requiring physical access or local credentials, making this vulnerability particularly dangerous for enterprise and service provider networks. This vulnerability directly impacts the availability aspect of the CIA triad and can result in extended network outages, service disruptions, and potential business continuity issues.
Mitigation strategies for this vulnerability require immediate patching of affected Cisco IOS devices with the latest security updates provided by Cisco. Network administrators should implement the recommended security patches and firmware updates that address the specific SSH server flaws identified in the bug IDs. Additionally, implementing network segmentation and access controls can help limit the attack surface by restricting SSH access to only authorized administrative users. Monitoring for unusual SSH connection patterns and implementing intrusion detection systems can provide early warning of potential exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security patches and following the principle of least privilege in network administration. Organizations should consider implementing redundant network paths and failover mechanisms to minimize the impact of potential exploitation attempts. This vulnerability serves as a reminder of the critical importance of timely security updates and proper network infrastructure hardening practices to prevent unauthorized access and service disruption in enterprise environments.