Unified Communications Flaw Let Attackers Execute Arbitrary Code

Cisco Unified Communications and Contact Center Solutions, known for their robustness, have recently been under scrutiny due to a critical vulnerability. 

This flaw exposes an unsettling prospect: an unauthenticated, remote attacker gaining the ability to execute arbitrary code on affected devices. In this article, we dissect the intricacies of this security lapse.

The vulnerability CVE-2024-20253 stems from the improper processing of user-provided data, allowing attackers to exploit the system by sending a carefully crafted message to a listening port. 

The consequence? The potential execution of arbitrary commands with the privileges of the web services user leads to an ominous scenario where the attacker could establish root access on the affected device.

The Affected Products and Exempted Solutions

The vulnerability affects several Cisco products, including Unified Communications Manager, IM & Presence Service, Session Management Edition, Contact Center Express, Unity Connection, and Virtualized Voice Browser.

Affected Devices

• Unified Communications Manager (Unified CM) (CSCwd64245)
• Unified Communications Manager IM & Presence Service (Unified CM IM&P) (CSCwd64276)
• Unified Communications Manager Session Management Edition (Unified CM SME) (CSCwd64245)
• Unified Contact Center Express (UCCX) (CSCwe18773)
• Unity Connection (CSCwd64292)
• Virtualized Voice Browser (VVB) (CSCwe18840)

However, Cisco clarifies that certain products, such as Customer Collaboration Portal and Unified Contact Center Enterprise, remain unscathed.

Cisco’s Response: Software Updates and Mitigation Measures

Cisco swiftly responded to this threat, releasing software updates to address the vulnerability. 

However, there are no workarounds available. The provided mitigation involves establishing access control lists (ACLs) on intermediary devices, limiting access to the ports of deployed services. 

Users are urged to refer to Cisco’s documentation for comprehensive guidance on mitigating the risk.

The report acknowledges Julien Egloff from Synacktiv for reporting this vulnerability, highlighting the collaborative efforts within the cybersecurity community to enhance digital defenses.

At present, the Cisco Product Security Incident Response Team (PSIRT) has no knowledge of any instances where the vulnerability outlined in this advisory has been publicly disclosed or exploited for malicious purposes.