How One Application Test Uncovered an Unexpected Opening in an Enterprise Call Tool

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Working as security consultants is highly rewarding. Companies depend on us to view their environment from the perspective of an attacker and find vulnerabilities that could enable threats to succeed. One of the most impactful parts of our role is when we’re the first to find a major vulnerability that could lead to a widespread compromise beyond just our client.

That’s what happened this year with the Cisco Unified Communications Manager (CUCM) IM & Presence appliance. We performed an application penetration test against it for one of our clients. While doing so, we discovered an opening that could effect anyone who uses this appliance. Read on to find out how we explored the product, how we broke it and how to put it back together.

What Is the CUCM Product?

The CUCM solution is a middleware component that allows enterprises to integrate their various communication devices and manage them using one platform. In short, it unifies voice, video, data and mobile applications on fixed and mobile networks. Starting with the Cisco Unified Communications 9.0, the Cisco Unified Presence technology is integrated within the CUCM. Nowadays, most people refer to this solution as the CUCM IM & Presence Service. Almost every customer that uses the Cisco Jabber instant messaging application has the CUCM IM & Presence deployment.

The Findings

During the pen test, we first tried to use the least possible privilege to pinpoint the vulnerabilities that the least trusted users can reach. Then, we created a replica of the appliance in a lab environment. Using several reverse engineering techniques, we extracted the source code of the web application used to manage the appliance.

Through both dynamic testing and analysis of the source code, we found the following vulnerabilities:

  • 3 x Structured Query Language (SQL) injection (CVE-2021-1355, CVE-2021-1364, CVE-2021-1282)
  • SQL injection leads to arbitrary code execution (CVE-2021-1363, CVE-2021-1365)
  • Path traversal (CVE-2021-1357)
  • Cross-site scripting (CVE-2021-1407, CVE-2021-1408)

The main objective was to find vulnerabilities that attackers could exploit to elevate their privilege on the appliance. At first, our…

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