CVE-2011-2586 in IOS
Summary
by MITRE
The HTTP client in Cisco IOS 12.4 and 15.0 allows user-assisted remote attackers to cause a denial of service (device crash) via a malformed HTTP response to a request for service installation, aka Bug ID CSCts12249.
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Analysis
by VulDB Data Team • 02/17/2019
The vulnerability described in CVE-2011-2586 represents a critical denial of service flaw within Cisco IOS software versions 12.4 and 15.0. This issue specifically affects the HTTP client implementation that handles service installation requests, creating a condition where malicious actors can exploit a malformed HTTP response to crash the targeted device. The vulnerability operates through a user-assisted remote attack vector, meaning that an attacker must convince a legitimate user to initiate a service installation request, but once triggered, the device becomes unavailable to authorized personnel and potentially impacts network operations.
The technical root cause of this vulnerability stems from inadequate input validation within the HTTP client component of Cisco IOS. When the device receives a malformed HTTP response during a service installation process, the parsing logic fails to properly handle unexpected data structures or malformed headers, leading to memory corruption or stack overflow conditions. This type of flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap data structures. The vulnerability specifically manifests when the HTTP client attempts to process HTTP responses that contain unexpected or malformed content that exceeds buffer boundaries or contains invalid data sequences that the parsing logic cannot properly interpret.
From an operational impact perspective, this vulnerability poses significant risks to network infrastructure availability and reliability. When a Cisco IOS device crashes due to this vulnerability, it results in complete service disruption for all network functions that depend on that device, including routing, switching, and security services. The attack requires minimal privileges and can be executed remotely, making it particularly dangerous in production environments where network availability is critical. Network administrators may experience extended downtime while troubleshooting and applying patches, potentially affecting business continuity and customer service levels. The vulnerability also creates opportunities for attackers to perform persistent denial of service attacks against critical network infrastructure, especially in environments where service installation requests are frequently made.
Mitigation strategies for CVE-2011-2586 should focus on immediate patch application and network segmentation. Cisco released IOS software updates that address the input validation issues in the HTTP client component, and organizations should prioritize applying these patches to all affected devices. Network administrators should also implement monitoring solutions to detect unusual HTTP traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and error handling in network device software, aligning with ATT&CK technique T1499.004 which covers network denial of service attacks. Additionally, organizations should consider implementing network access controls to limit exposure of vulnerable devices to untrusted networks and establish incident response procedures for handling device crashes and service disruptions. Security teams should also conduct regular vulnerability assessments to identify other potential buffer overflow conditions in network infrastructure software and maintain up-to-date threat intelligence regarding similar vulnerabilities in network operating systems.