.png){kind=logo}
Critical Cisco Unified Communications Zero-Day (CVE-2024-20253) Actively Exploited: Millions of Enterprises at Risk
- Rescana
- 5 minutes ago
- 4 min read
Executive Summary
A critical zero-day vulnerability in Cisco Unified Communications (UC) products, tracked as CVE-2024-20253, has been discovered and is being actively exploited in the wild. This flaw impacts millions of enterprise and government users globally, as it affects core collaboration infrastructure such as Cisco Unified Communications Manager (Unified CM), Cisco Unity Connection, and Cisco Webex Calling Dedicated Instance. The vulnerability allows unauthenticated remote attackers to execute arbitrary commands on the underlying operating system, potentially leading to full system compromise. The exploitation of this flaw has prompted urgent advisories from Cisco, the U.S. Cybersecurity and Infrastructure Security Agency (CISA), and multiple threat intelligence sources. Immediate patching is required, as no workarounds exist and exploitation is ongoing.
Threat Actor Profile
The exploitation of CVE-2024-20253 has not yet been attributed to a specific advanced persistent threat (APT) group or nation-state actor. However, the attack pattern and rapid weaponization suggest involvement by both opportunistic cybercriminals and potentially more sophisticated actors. The threat landscape indicates that actors are leveraging automated scanning tools to identify vulnerable Cisco UC instances exposed to the internet, followed by targeted exploitation. The lack of authentication required for exploitation makes this vulnerability attractive to a broad spectrum of threat actors, from ransomware operators to state-sponsored groups seeking initial access to high-value networks.
Technical Analysis of Malware/TTPs
CVE-2024-20253 is a remote code execution (RCE) vulnerability resulting from improper input validation in the web-based management interface of affected Cisco UC products. Specifically, the flaw is rooted in the way the HTTP request parameters are parsed and handled, allowing attackers to inject and execute arbitrary system commands with the privileges of the web server process. In many default deployments, this can lead to privilege escalation to root.
The technical exploitation chain involves sending a specially crafted HTTP POST request to the management interface, embedding malicious payloads in parameters that are insufficiently sanitized. Upon successful exploitation, attackers can deploy web shells, establish reverse shells, or download and execute additional malware. Post-exploitation tactics observed in the wild include lateral movement using harvested credentials, deployment of ransomware payloads, and exfiltration of sensitive configuration data.
Detection of exploitation attempts can be achieved by monitoring for anomalous HTTP requests to the management interface, especially those containing suspicious command sequences or encoded payloads. Cisco has released updated Snort rules (65750, 65751, and 65752) to detect exploitation attempts at the network level.
Exploitation in the Wild
Multiple security research organizations and Cisco PSIRT have confirmed active exploitation of CVE-2024-20253. Attackers are scanning for and targeting internet-exposed Cisco UC management interfaces, with successful compromises reported across North America, Europe, and Asia-Pacific. The CISA has added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, mandating federal agencies to patch immediately.
There is evidence of automated exploitation campaigns, with attackers leveraging mass scanning tools to identify vulnerable endpoints. In some cases, exploitation has led to the deployment of ransomware and the theft of sensitive voice and messaging data. No public proof-of-concept (PoC) code has been released, but private exploit kits are circulating in underground forums, increasing the risk of widespread attacks.
Victimology and Targeting
The primary targets of this exploitation campaign are large enterprises, government agencies, and service providers that rely on Cisco UC infrastructure for mission-critical communications. Sectors most affected include finance, healthcare, government, and telecommunications, where Cisco UC products are widely deployed. Attackers are prioritizing organizations with externally accessible management interfaces, weak network segmentation, and delayed patch management processes.
Victims have reported disruptions to voice and messaging services, unauthorized access to sensitive communications, and in some cases, full compromise of the underlying server infrastructure. The impact is amplified in environments where Cisco UC systems are integrated with other core IT assets, enabling attackers to pivot laterally and escalate privileges across the network.
Mitigation and Countermeasures
Immediate action is required to mitigate the risk posed by CVE-2024-20253. Organizations must apply the security patches released by Cisco for all affected products, including Unified Communications Manager, Unity Connection, and Webex Calling Dedicated Instance. There are no viable workarounds; patching is the only effective mitigation.
Administrators should ensure that management interfaces are not exposed to the public internet and are protected by strong access controls and network segmentation. Continuous monitoring for exploitation attempts is critical; deploy the latest Snort rules (65750, 65751, 65752) and review HTTP access logs for anomalous activity. Incident response teams should conduct thorough forensic analysis of potentially compromised systems, looking for evidence of web shells, unauthorized user accounts, and lateral movement.
Organizations are advised to review their third-party risk management (TPRM) processes to ensure that all vendors and partners using Cisco UC products are also applying patches promptly. Regular vulnerability scanning and penetration testing should be conducted to identify and remediate any residual exposure.
References
About Rescana
Rescana is a leader in third-party risk management (TPRM), providing organizations with a comprehensive platform to continuously monitor, assess, and mitigate cyber risks across their entire supply chain. Our advanced analytics and automation capabilities empower security teams to identify vulnerabilities, prioritize remediation, and ensure compliance with industry standards. For more information about how Rescana can help strengthen your organization’s cyber resilience, we are happy to answer questions at ops@rescana.com.