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February 24, 2024

How to Fix CVE-2024-20272 - An Unauthenticated Arbitrary File Upload Vulnerability in Cisco Unity Connection?

How to Fix CVE-2024-20272 - An Unauthenticated Arbitrary File Upload Vulnerability in Cisco Unity Connection

Cisco recently published an advisory detailing a critical vulnerability in its Unity Connection unified messaging solution that could allow an attacker to remotely upload malicious files and execute arbitrary commands.

Tracked as CVE-2024-20272, this vulnerability stems from a lack of authentication enforcement in a specific API that handles file uploads. Attackers can exploit this to store malicious files and payloads on vulnerable Unity Connection servers without needing to authenticate.

With a high severity CVSS base score of 7.3, successful exploitation of this flaw can enable remote code execution and privilege escalation on the underlying operating system. Given Unity Connection's widespread use for mission-critical voice messaging, enterprises must urgently assess and mitigate this high-risk vulnerability.

This post provides an overview of the CVE-2024-20272 arbitrary file upload vulnerability impacting Cisco Unity Connection deployments globally. We summarize the technical details, affected product versions, and most importantly - how administrators can securely fix this flaw by upgrading to patched Cisco releases.

A Short Introduction to Cisco Unity Connection

Cisco Unity Connection is a feature-rich unified messaging and voicemail solution used by enterprises globally. It enables users to conveniently access voice messages from their email inbox, web browser, mobile devices as well as IP phones.

Key capabilities offered by Unity Connection include:

  • Flexible voice message access: Users can retrieve, manage, forward voicemails through various interfaces like email, Jabber, phones. It also allows speech-to-text transcription to read messages.

  • Video integration: Users can set up video greetings, auto attendants, and even send video messages phone-to-phone.

  • High availability: Unity Connection supports redundancy, failover capabilities for 24/7 mission-critical deployments through clustering.

  • Virtualization: It is delivered as a virtual machine completely decoupled from hardware. This simplifies deployment on Cisco UCS or other virtualization platforms.

  • Unified management: Prime Collaboration provides unified provisioning, monitoring, reporting for the entire voice/video ecosystem including Unity Connection.

With its rich messaging capabilities and enterprise-grade reliability, scalability, Cisco Unity Connection is trusted by large corporations, government agencies across complex global deployments.

Summary of CVE-2024-20272

  • CVE ID: CVE-2024-20272

  • CVSSv3 Base Score: 7.3 High

  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Description: An unauthenticated arbitrary file upload vulnerability in Cisco Unity Connection web interface

This high severity vulnerability allows an unauthenticated remote attacker to upload arbitrary malicious files onto vulnerable Unity Connection servers. The vulnerability stems from lack of authentication enforcement in a specific API used for file uploads. There is also no proper server-side validation of the files being uploaded through this API.

By abusing this flaw, a remote unauthenticated attacker can leverage this API to store malicious files and payloads like web shells onto the system. This grants them a foothold to then access the underlying operating system.

Successful exploitation enables arbitrary remote code execution, planting backdoors and privilege escalation to root privileges on the OS. Attackers can thus fully compromise Unity Connection, persistently control the voice messaging environment and launch further attacks into the corporate network.

Given its ease of exploitation and high impact, enterprises must urgently mitigate this arbitrary remote file upload vulnerability.

Products Vulnerable

Cisco has confirmed that the following versions of Unity Connection are vulnerable to CVE-2024-20272:

  • Cisco Unity Connection 12.5 and earlier releases

  • This includes versions 12.5.1 SU3 and prior builds

  • As well as 12.0.1, 11.5, 11.0, 10.5 releases

Essentially, all supported versions of Unity Connection prior to release 14 are impacted by this high severity arbitrary remote file upload flaw.

How to Fix CVE-2024-20272?

Cisco has released software updates for Cisco Unity Connection to address the arbitrary file upload vulnerability tracked as CVE-2024-20272.

Customers using the following vulnerable versions should upgrade to the corresponding fixed Unity Connection release:

  • Unity Connection 12.5 and prior - upgrade to release 14

  • Unity Connection 14 affected builds - install hotfix COP file provided by Cisco

The updated releases and hotfixes address the authentication and input validation flaws that enable unauthenticated arbitrary file uploads.

As per the Cisco advisory, Unity Connection version 15 is not affected by CVE-2024-20272, so no fixes are required.

Cisco has confirmed there are no workarounds that fully mitigate this vulnerability. Disabling the vulnerable servlet is prone to misconfiguration and not recommended.

So affected organizations must urgently update production Unity Connection deployments to the latest available release. For added assurance, information security teams can consider restricting access to vulnerable builds still pending upgrades.

We hope this post helps you know how to fix CVE-2024-20272 - an unauthenticated Arbitrary File Upload Vulnerability in Cisco Unity Connection. Thanks for reading this post. Please share this post and help secure the digital world.Visit our website, and our social media page on FacebookLinkedInTwitterTelegramTumblrMedium, and Instagram and subscribe to receive updates like this.

Arun KL

Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.

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