Vulnerability Found in SimpleMDM Apple Device Management Solution

An XML external entity (XXE) vulnerability has been found and patched in the SimpleMDM Apple device management solution, but the researcher who found the flaw and the vendor disagree on its impact.

SimpleMDM is an increasingly popular mobile device management (MDM) solution used by companies such as FedEx, Deloitte and the Discovery Channel.

Nishaanth Guna, senior security researcher at mobile security startup AppKnox, discovered an XXE vulnerability on the a.simplemdm.com domain. Since it appeared to be a production server, Guna only pinged his own server to verify the issue, but did not escalate it further and immediately reported it to SimpleMDM.

However, he believes the vulnerability could have been exploited for various purposes, including port scanning, reading arbitrary files from the system, and taking over the admin portal used to manage devices.

“The baseline for creating a proof-of-concept for XXE is port scanning and verifying if you get a hit from the vulnerable server,” Guna told SecurityWeek. “So, technically if the server is accepting an external DTD [document type definition], which is true in this case, an attacker can craft a different request to read files from the server, which always happens if the server is vulnerable to XXE.”

According to the researcher, the impacted servers are exposed to the internet and the vulnerability could have been exploited without authentication by sending a specially crafted request. All an attacker needed to launch an exploit was the address of the targeted server.

Guna believes that the vulnerability could have been exploited for port scanning, which allows an attacker to scan other devices inside and outside the network.

“For instance, if the application server is hosted at simplemdm.com, an attacker can exploit this and port scan, say facebook.com, and Facebook’s logs will show that simplemdm.com scanned their network,” Guna explained.

He added, “An attacker can also read files from the host where the application is hosted. Once he compromises the host, he can try to attack the devices managed by the MDM.”

Guna reported his findings to SimpleMDM on August 21 and a patch was rolled out within hours. The researcher has praised the company for its quick and professional response, despite the fact that it does not have a bug bounty program.

However, SimpleMDM does not appear to agree with Guna’s assessment of the vulnerability’s impact.

In a statement sent to SecurityWeek, the vendor said, “The vulnerability, when exploited, allowed a third party to provoke a SimpleMDM web server to fetch a publicly accessible web document, such as an HTML page. No further behavior could be provoked beyond the fetch of a page, and an ‘invalid request’ response was then provided to the requestor. The vulnerability did not allow local file access, as can be the case in XXE vulnerabilities.”

The company added, “Our intrusion detection, vulnerability detection, logs, and systems for detecting abnormal behavior show no indication of this vulnerability being exploited. This vulnerability does not relate to customer data and no customer data was nor could have been accessed.”

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