CVE-2000-0984 in iOS
Summary
by MITRE
The HTTP server in Cisco IOS 12.0 through 12.1 allows local users to cause a denial of service (crash and reload) via a URL containing a "?/" string.
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Analysis
by VulDB Data Team • 09/17/2024
The vulnerability identified as CVE-2000-0984 represents a critical denial of service flaw within Cisco IOS software versions 12.0 through 12.1. This issue specifically affects the HTTP server component of Cisco's networking operating system, which is widely deployed across enterprise and corporate networks for managing network infrastructure. The vulnerability stems from improper input validation within the HTTP server implementation, creating a condition where malformed URL requests can trigger system instability. The flaw manifests when a local user crafts a specific URL containing the "?/" string sequence, which the system processes without adequate sanitization or error handling mechanisms. This particular string combination exploits a parsing weakness in the HTTP server's URL handling logic, leading to unpredictable behavior and system-wide disruption.
The technical exploitation of this vulnerability occurs through the manipulation of Uniform Resource Locator syntax within HTTP requests. When the Cisco IOS HTTP server encounters a URL containing the "?/" pattern, the internal parsing routine fails to properly handle the malformed input, causing memory corruption or stack overflow conditions. This processing error ultimately results in the complete crash of the HTTP server process, which frequently cascades into a full system reload or reboot. The vulnerability is classified as a local privilege escalation vector since it can be triggered by users with minimal access rights, though the impact extends beyond simple privilege levels due to the critical nature of network infrastructure services. The flaw demonstrates characteristics consistent with CWE-121, heap-based buffer overflow, and CWE-122, stack-based buffer overflow, as the parsing failure leads to memory corruption in the HTTP server's processing stack.
The operational impact of CVE-2000-0984 extends far beyond simple service disruption, potentially affecting entire network operations and business continuity. Organizations relying on Cisco IOS for web-based management interfaces, configuration access, or network monitoring services face significant risk when this vulnerability exists in their network infrastructure. The automatic system reload behavior means that network administrators may experience unexpected downtime without warning, potentially coinciding with critical network operations or maintenance windows. This vulnerability particularly affects environments where the HTTP server is enabled for administrative access, as local users could leverage this flaw to repeatedly disrupt services and potentially create a persistent denial of service condition. The attack vector is relatively simple to execute, requiring only basic knowledge of URL construction, making it accessible to threat actors with minimal technical expertise. Network availability and reliability are fundamentally compromised, as the HTTP server becomes unusable until manual intervention or system reboot occurs.
Mitigation strategies for this vulnerability require immediate implementation of network access controls and configuration modifications. Organizations should disable the HTTP server functionality on affected Cisco IOS devices when it is not strictly required for network management purposes, as outlined in the ATT&CK technique T1210 for exploitation of network-based services. Cisco released patches and updated IOS versions addressing this specific vulnerability, making software upgrades the primary recommended solution for organizations maintaining affected systems. Network segmentation and access control measures should be implemented to limit local user access to network devices, reducing the attack surface for exploitation. Additionally, implementing network monitoring tools that can detect anomalous HTTP traffic patterns or unusual URL requests may provide early warning of attempted exploitation. Configuration audits should verify that HTTP server services are only enabled on devices where they are absolutely necessary, with proper authentication and authorization controls in place. The vulnerability also highlights the importance of regular security assessments and patch management procedures, as this flaw existed for several years without proper detection or remediation in many network environments. Organizations should consider implementing network intrusion detection systems that can identify and alert on suspicious HTTP request patterns that may indicate exploitation attempts.