CVE-2013-1241 in IOS
Summary
by MITRE
The ISM module in Cisco IOS on ISR G2 routers does not properly handle authentication-header packets, which allows remote authenticated users to cause a denial of service (module reload) via a series of malformed packets, aka Bug ID CSCub92025.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/10/2021
The vulnerability identified as CVE-2013-1241 affects the ISM module within Cisco IOS operating system running on ISR G2 routers. This issue represents a significant security flaw that impacts the stability and availability of network infrastructure components. The ISM module is responsible for handling specific network protocols and authentication mechanisms, making it a critical component for maintaining secure communications within enterprise networks. When this module fails to properly process authentication-header packets, it creates an exploitable condition that can be leveraged by malicious actors to disrupt network services.
The technical flaw manifests in the improper handling of malformed authentication-header packets that are sent to the affected routers. These packets contain malformed data structures within their authentication headers that the ISM module cannot process correctly. The vulnerability specifically targets the packet parsing logic within the ISM module, where the system fails to validate incoming packet structures before attempting to process them. This lack of proper input validation creates a condition where specially crafted packets can trigger unexpected behavior in the router's memory management and processing routines, ultimately leading to system instability.
The operational impact of this vulnerability is severe as it enables authenticated remote attackers to execute a denial of service attack against the affected network infrastructure. An attacker who has gained authentication credentials to access the router can systematically send malformed packets to cause the ISM module to crash and reload. This module reload process results in temporary network disruption as the router must restart its services, potentially causing service outages for network users. The vulnerability is particularly concerning because it requires only authentication credentials, which are often easier to obtain than exploiting unauthenticated vulnerabilities, making it a realistic threat for network administrators to consider.
Cisco has assigned the bug ID CSCub92025 to track this vulnerability, which is classified under the Common Weakness Enumeration framework as a weakness related to improper input validation and buffer overflows. The vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under the technique of "Denial of Service" and specifically relates to "Resource Exhaustion" and "System Resource Exhaustion" tactics. Network administrators should consider this vulnerability as part of their broader security posture assessment, particularly when evaluating the resilience of their core network infrastructure against targeted attacks. The issue demonstrates the importance of proper input validation and error handling in network protocol implementations, as even authenticated access can be leveraged to cause significant service disruption.
Mitigation strategies for this vulnerability include applying the latest security patches released by Cisco, which address the flawed packet handling logic in the ISM module. Network administrators should also implement network segmentation and access controls to limit the number of authenticated users who can reach the affected routers. Monitoring network traffic for unusual packet patterns and implementing intrusion detection systems can help identify potential exploitation attempts. Additionally, organizations should maintain updated network device inventories and ensure that all ISR G2 routers are running patched firmware versions to prevent unauthorized exploitation of this vulnerability. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and proper network access controls to prevent authenticated attackers from causing service disruptions through carefully crafted packet sequences.