CVE-2018-0485 in ISR G2
Summary
by MITRE
A vulnerability in the SM-1T3/E3 firmware on Cisco Second Generation Integrated Services Routers (ISR G2) and the Cisco 4451-X Integrated Services Router (ISR4451-X) could allow an unauthenticated, remote attacker to cause the ISR G2 Router or the SM-1T3/E3 module on the ISR4451-X to reload, resulting in a denial of service (DoS) condition on an affected device. The vulnerability is due to improper handling of user input. An attacker could exploit this vulnerability by first connecting to the SM-1T3/E3 module console and entering a string sequence. A successful exploit could allow the attacker to cause the ISR G2 Router or the SM-1T3/E3 module on the ISR4451-X to reload, resulting in a DoS condition on an affected device.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability described in CVE-2018-0485 represents a critical denial of service weakness affecting Cisco Second Generation Integrated Services Routers and the specific SM-1T3/E3 module within the ISR4451-X platform. This flaw resides in the firmware implementation of these network devices, creating an exploitable condition that can be leveraged by remote attackers without requiring authentication credentials. The vulnerability specifically impacts the console interface handling mechanisms of the affected hardware components, making it particularly concerning for network infrastructure security. The flaw demonstrates poor input validation practices that can be exploited to disrupt network services and compromise availability of critical routing equipment.
The technical root cause of this vulnerability stems from improper handling of user input within the console interface of the SM-1T3/E3 module. When an attacker establishes a connection to the console and inputs a specific string sequence, the system fails to properly validate or sanitize this input before processing it. This lack of proper input validation creates a condition where maliciously crafted input can trigger unexpected behavior in the firmware's console handling routines. The vulnerability manifests as a system reload operation that results in complete service disruption, effectively rendering the affected router or module unavailable to legitimate network traffic. This type of flaw aligns with CWE-121, which describes buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap-based data structures, though the specific implementation appears to involve console input handling rather than memory corruption.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network reliability and availability for organizations relying on these Cisco ISR G2 platforms. Network administrators may experience unexpected outages when attackers exploit this condition, particularly in environments where these routers serve as critical network infrastructure components. The vulnerability's remote exploitability means that attackers do not require physical access to the devices, significantly expanding the potential attack surface. Organizations may face service interruptions that affect business operations, especially in mission-critical network environments where router availability is paramount. The DoS condition can persist until manual intervention occurs to restart the affected system, potentially causing cascading failures in network connectivity.
Mitigation strategies for this vulnerability should focus on implementing immediate firmware updates from Cisco as recommended in their security advisories. Network administrators should also consider restricting console access to authorized personnel only, implementing network segmentation to limit potential attack vectors, and monitoring console sessions for suspicious activity. The implementation of access control lists and proper network monitoring can help detect and prevent exploitation attempts. Organizations should also review their network access policies to ensure that console interfaces are not unnecessarily exposed to untrusted networks. This vulnerability highlights the importance of secure firmware development practices and proper input validation mechanisms. The ATT&CK framework categorizes this type of vulnerability under T1499, which covers network denial of service attacks, and T1072, which addresses software deployment methods that can be exploited to gain system access. Regular security assessments and vulnerability scanning of network infrastructure should be conducted to identify similar input validation weaknesses in other network components.