CVE-2003-1398 in IOS
Summary
by MITRE
Cisco IOS 12.0 through 12.2, when IP routing is disabled, accepts false ICMP redirect messages, which allows remote attackers to cause a denial of service (network routing modification).
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Analysis
by VulDB Data Team • 03/08/2021
Cisco IOS versions 12.0 through 12.2 contain a critical vulnerability in their Internet Control Message Protocol implementation that manifests when IP routing is disabled on the device. This vulnerability stems from the failure of the routing protocol to properly validate incoming ICMP redirect messages, allowing malicious actors to inject false redirect information into the network infrastructure. The flaw exists within the network layer processing mechanisms that handle ICMP protocol messages, specifically targeting the routing table update procedures that occur when IP routing is disabled. When an attacker sends crafted ICMP redirect messages to a vulnerable Cisco IOS device, the system processes these messages without proper validation, leading to unauthorized modification of routing information. This vulnerability directly maps to CWE-224, which addresses improper handling of potentially dangerous input data, and aligns with ATT&CK technique T1562.001 for "Impairing Security Tools" and T1498 for "Network Denial of Service." The security implications extend beyond simple service disruption as attackers can manipulate network paths to redirect traffic through unauthorized routes, potentially enabling man-in-the-middle attacks or traffic interception. The impact of this vulnerability is particularly severe in environments where network security is paramount, as it allows remote attackers to compromise network integrity and availability. When IP routing is disabled, the device should not process routing information from external sources, yet this vulnerability bypasses that restriction through the improper handling of ICMP redirect messages. The attack vector requires minimal privileges and can be executed remotely, making it particularly dangerous for network infrastructure devices that are often exposed to untrusted network segments. Network administrators face significant challenges in detecting such attacks as the false redirect messages appear legitimate to the device's processing engine. The vulnerability demonstrates a fundamental flaw in the input validation and trust model implementation within the IOS routing stack, where external routing information is accepted without proper authentication or verification mechanisms. This weakness creates an attack surface that can be exploited to cause persistent network disruption and potentially enable more sophisticated attacks that leverage the altered routing paths. The affected versions of Cisco IOS represent a broad range of network infrastructure devices that are widely deployed in enterprise and service provider environments, amplifying the potential impact of this vulnerability across multiple network domains.
The operational impact of CVE-2003-1398 extends far beyond simple denial of service conditions, as it fundamentally compromises the integrity of network routing information within affected Cisco devices. When attackers successfully exploit this vulnerability, they can manipulate the routing tables of network devices to redirect traffic through unintended paths, potentially causing complete network outages or creating security holes that allow further attacks. The vulnerability's ability to affect devices with IP routing disabled creates a particularly dangerous scenario where network administrators expect certain security boundaries to be maintained. This flaw represents a breakdown in the principle of least privilege and proper input validation, as the system accepts potentially malicious routing information without proper verification. The exploitability of this vulnerability is enhanced by the fact that ICMP redirect messages are commonly used in legitimate network operations, making it difficult to distinguish between normal traffic and malicious activity. Organizations that rely on Cisco IOS devices for network security and routing functions face significant operational risks when this vulnerability exists in their infrastructure. The impact on network availability is immediate and can persist until the device is manually reset or the vulnerability is patched, creating potential service disruption that may last for extended periods. Network monitoring systems may not immediately detect this attack vector since the false redirect messages appear to conform to standard ICMP protocols, allowing attackers to maintain their influence over network routing for extended periods. This vulnerability particularly affects network infrastructure that requires strict control over routing information flow, such as those implementing security zones or multi-layered network architectures.
Mitigation strategies for CVE-2003-1398 require immediate implementation of network security controls to prevent exploitation while long-term solutions focus on patch management and network architecture improvements. The most effective immediate countermeasure involves disabling ICMP redirect processing on affected Cisco IOS devices through configuration changes that prevent the acceptance of false redirect messages. Network administrators should implement ingress filtering and egress filtering rules to block ICMP redirect messages from untrusted sources, effectively creating a perimeter defense against this specific attack vector. The implementation of proper access control lists and routing protocol authentication mechanisms can help prevent unauthorized routing information from being processed by network devices. Organizations should also consider implementing network segmentation strategies that reduce the potential impact of routing manipulation attacks and provide multiple layers of defense. Cisco has released patches and software updates specifically addressing this vulnerability in affected IOS versions, making timely patch deployment a critical component of the remediation strategy. Network monitoring systems should be enhanced to detect unusual routing table changes or ICMP redirect message patterns that may indicate exploitation attempts. The vulnerability highlights the importance of maintaining current network security practices and regular vulnerability assessments to identify and remediate similar issues before they can be exploited. Security teams should also implement network behavior monitoring to detect anomalous routing patterns that may result from successful exploitation. Long-term mitigation requires a comprehensive approach that includes regular security assessments, network architecture reviews, and continuous monitoring of network protocols to ensure that similar validation flaws do not exist in other network infrastructure components. The vulnerability serves as a reminder of the critical importance of proper input validation and the need for robust security controls in network infrastructure devices.