CVE-2000-0380 in IOS
Summary
by MITRE
The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.
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Analysis
by VulDB Data Team • 09/21/2024
The vulnerability identified as CVE-2000-0380 represents a critical denial of service weakness within Cisco's Internetwork Operating System IOS implementation. This flaw specifically affects network infrastructure devices including routers and switches that operate with IOS versions ranging from 11.1 through 12.1. The vulnerability manifests through the HTTP service component that is integrated into these network devices, creating an exploitable condition that can be leveraged by remote attackers to disrupt network operations. The issue stems from inadequate input validation within the HTTP service parser, where the system fails to properly handle certain URL sequences that contain double percent characters.
The technical mechanism of exploitation involves crafting a malicious URL that contains a %% string sequence, which triggers a parsing error within the IOS HTTP service. When the affected device receives such a malformed request, the HTTP service component becomes unstable and typically results in a complete system crash or reboot. This occurs because the IOS HTTP parser does not properly sanitize or handle the double percent encoding that would normally be processed by compliant HTTP implementations. The vulnerability exploits a fundamental flaw in the input processing logic, where the system attempts to interpret the double percent sequence in a manner that causes memory corruption or stack overflow conditions.
The operational impact of this vulnerability extends beyond simple service disruption, as it can lead to significant network downtime and potential business continuity issues for organizations relying on these network devices. When exploited, the denial of service condition affects not only the HTTP service but can also potentially impact other network services running on the same device. Network administrators face the challenge of maintaining availability while the affected devices are taken offline for repairs or updates. The vulnerability affects a substantial number of Cisco devices deployed in enterprise and service provider networks, making it a widespread concern for network security teams.
Mitigation strategies for this vulnerability include immediate implementation of IOS software updates provided by Cisco, which address the parsing flaw in the HTTP service component. Organizations should also consider implementing access control measures to restrict HTTP service access to trusted networks only, thereby reducing the attack surface. Network segmentation and firewall rules can help prevent unauthorized access to the affected devices. Additionally, monitoring systems should be configured to detect unusual HTTP traffic patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-129, which addresses issues related to input validation and improper handling of special characters in network services, and corresponds to ATT&CK technique T1499.004 for network denial of service attacks. The remediation process requires careful planning to avoid service disruption during patch deployment, particularly in mission-critical network environments where device availability is paramount.