CVE-2017-6690 in ASR 5000
Summary
by MITRE
A vulnerability in the file check operation of Cisco ASR 5000 Series Aggregated Services Routers running the Cisco StarOS operating system could allow an authenticated, remote attacker to overwrite or modify arbitrary files on an affected system. More Information: CSCvd73726. Known Affected Releases: 21.0.v0.65839 21.3.M0.67005. Known Fixed Releases: 21.4.A0.67087 21.4.A0.67079 21.4.A0.67013 21.3.M0.67084 21.3.M0.67077 21.3.M0.66994 21.3.J0.66993 21.1.v0.67082 21.1.V0.67083.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2017-6690 represents a critical file system manipulation flaw within the Cisco ASR 5000 Series Aggregated Services Routers that operates on the Cisco StarOS operating system. This security weakness stems from insufficient input validation during file check operations, creating a path for authenticated remote attackers to exploit the system's file handling mechanisms. The vulnerability specifically affects the router's ability to properly validate file operations, allowing malicious actors with legitimate authentication credentials to perform unauthorized file modifications. The affected versions include several releases from the 21.0 and 21.3 release lines, with the most recent fixed releases spanning multiple version branches including 21.4.A0, 21.3.M0, 21.3.J0, and 21.1.v0 releases.
The technical nature of this vulnerability falls under the category of improper input validation as classified by CWE-20, where the system fails to properly validate or sanitize inputs during file operations. Attackers can leverage this weakness to overwrite or modify arbitrary files on the affected system, potentially compromising the integrity of critical system files, configuration data, or operational components. The flaw enables a remote authenticated attacker to manipulate the router's file system in ways that could disrupt normal operations, potentially leading to complete system compromise. This type of vulnerability represents a significant risk in network infrastructure devices where unauthorized file modifications can have cascading effects on network security and availability.
The operational impact of CVE-2017-6690 extends beyond simple file corruption, as it provides attackers with a mechanism to potentially escalate privileges and gain deeper access to the affected router's operational environment. Network administrators face the risk of unauthorized configuration changes that could redirect traffic, disable security features, or create backdoor access points. The vulnerability's remote exploitation capability means attackers do not require physical access to the device, making it particularly dangerous in environments where network access is granted to multiple users or where authentication credentials might be compromised. This flaw can be categorized under ATT&CK technique T1070.004 for file and directory permissions modification, as it allows for unauthorized file system modifications that could affect system integrity and security posture.
Mitigation strategies for this vulnerability require immediate deployment of the patched releases provided by Cisco, including versions 21.4.A0.67087, 21.4.A0.67079, 21.4.A0.67013, 21.3.M0.67084, 21.3.M0.67077, 21.3.M0.66994, 21.3.J0.66993, 21.1.v0.67082, and 21.1.V0.67083. Organizations should also implement network segmentation to limit access to these critical devices, enforce strict access controls, and monitor for suspicious file modification activities. The vulnerability's classification as a privilege escalation risk warrants additional security measures including regular security audits, implementation of least privilege principles, and enhanced monitoring of system file changes. Network security teams should also consider implementing intrusion detection systems capable of identifying anomalous file system activities that could indicate exploitation attempts of this vulnerability.