CVE-2017-6624 in IOS
Summary
by MITRE
A vulnerability in Cisco IOS 15.5(3)M Software for Cisco CallManager Express (CME) could allow an unauthenticated, remote attacker to make unauthorized phone calls. The vulnerability is due to a configuration restriction in the toll-fraud protections component of the affected software. An attacker could exploit this vulnerability to place unauthorized, long-distance phone calls by using an affected system. Cisco Bug IDs: CSCuy40939.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/22/2020
The vulnerability identified as CVE-2017-6624 represents a critical security flaw in Cisco IOS 15.5(3)M Software running on Cisco CallManager Express devices. This weakness stems from inadequate configuration restrictions within the toll-fraud protections component, creating a pathway for unauthorized remote exploitation. The vulnerability specifically affects Cisco CallManager Express implementations where proper access controls have not been properly enforced, potentially allowing malicious actors to manipulate telephony systems without authentication. The flaw exists in the underlying software configuration that governs call routing and authorization processes, making it particularly dangerous for organizations relying on voice communication infrastructure for business operations.
The technical exploitation of this vulnerability occurs through manipulation of the toll-fraud protection mechanisms that are designed to prevent unauthorized long-distance calling. Attackers can leverage this configuration gap to bypass authentication requirements and place unauthorized phone calls through the affected system. The vulnerability essentially removes the protective barriers that should prevent arbitrary call initiation, allowing remote attackers to utilize the telephony infrastructure for fraudulent purposes. This type of flaw falls under CWE-284, which addresses improper access control, specifically targeting the authorization mechanisms that should govern telephone call permissions within enterprise communication systems.
The operational impact of this vulnerability extends beyond simple unauthorized calling, as it creates potential for significant financial losses and operational disruption. Organizations may face substantial charges from unauthorized long-distance calls while simultaneously experiencing compromised communication integrity. The remote nature of the exploit means that attackers can operate from any location with network access, making detection and attribution challenging. This vulnerability particularly affects enterprises that rely heavily on voice communication for business operations, as unauthorized calls could disrupt normal business processes while generating unexpected costs. The flaw also creates potential for further attacks, as successful exploitation may provide a foothold for additional malicious activities within the network infrastructure.
Mitigation strategies for CVE-2017-6624 should focus on implementing proper configuration controls within the Cisco IOS software. Organizations must ensure that toll-fraud protection mechanisms are properly configured and enforced, including implementing strict access controls for telephony management interfaces. Network segmentation and monitoring of telephony traffic can help detect unauthorized call patterns and potential exploitation attempts. Cisco recommends applying the appropriate software patches and updates to address the configuration restriction that enables this vulnerability. Security teams should also implement continuous monitoring of call logs and establish alerting mechanisms for unusual calling patterns that could indicate exploitation attempts. The remediation process aligns with ATT&CK technique T1071.004, which involves application layer protocol usage for command and control communications, as the vulnerability enables unauthorized communication channels that could be leveraged for further attacks. Organizations should also review and strengthen their overall telephony security posture, including implementing proper network access controls and regular security assessments of voice communication systems to prevent similar configuration-based vulnerabilities from compromising their infrastructure.