Critical Vulnerabilities Found in Prima FlexAir Access Control System

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) this week published an advisory to warn of multiple vulnerabilities access control systems made by Prima Systems.

The vulnerabilities impact Prima FlexAir Versions 2.3.38 and prior, and are considered Critical, as they can be exploited remotely and do not require advanced hacking skills, reveals the recently created CISA, an operational component under Department of Homeland Security (DHS). 

Prima’s FlexAir is used to control access to things such as elevators, door locks, parking lot gates, and even mailboxes.

“Exploitation of these vulnerabilities may allow an attacker to execute commands directly on the operating system, upload malicious files, perform actions with administrative privileges, execute arbitrary code in a user’s browser, discover login credentials, bypass normal authentication, and have full system access,” CISA notes in an advisory.

The vulnerabilities were discovered by Applied Risk security researcher Gjoko Krstic, who published details on them in May (PDF). According to Krstic, successful exploitation may provide an unauthenticated attacker with full system access.

The most important of the flaws is CVE-2019-7670, an OS command injection featuring a CVSS score of 10. The issue is that, when constructing an OS command using externally-influenced input, the application “incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.” 

Next in line is CVE-2019-7669, an improper validation of file extensions when uploading files. Featuring a CVSS score of 9.1, the vulnerability could allow a remote authenticated attacker to upload and execute malicious applications within the application’s web root with root privileges, CISA’s advisory reads. 

A series of authentication issues were also discovered in the platform, including the fact that it allows authentication using the MD5 hash value of the password (CVE-2019-7666 – CVSS score 7.5), or that the flash version of the web interface contains hard-coded username and password (CVE-2019-7672 – CVSS score 8.8).

Furthermore, the security researcher discovered that the application generates database backup files with a predictable name (CVE-2019-7667 – CVSS score 8.1), which could allow an attacker to use brute-force attacks to identify the database backup file name. The attacker could then download the database and disclose login information, thus gaining full access to the system.

Krstic also found a Cross-Site Request Forgery flaw (CVE-2019-7281 – CVSS score 5.0), which may allow attackers to perform actions with admin privileges when the user accesses a malicious website, and a Cross-Site Scripting bug (CVE-2019-7671 – CVSS score 5.4), which may allow an attacker to execute arbitrary code in a user’s browser session in context of an affected site.

Other issues are CVE-2019-7280 (of an insufficient length, the session-ID can be exploited by brute-force), and CVE-2019-9189 (the application allows the upload of arbitrary Python scripts when configuring the main central controller).

Prima Systems, CISA reveals, has addressed these vulnerabilities in version 2.5.12 of the application. 

“To update to the latest firmware, each user should select the “Check for Upgrade” option in the “Centrals” menu in the GUI. The user’s controller will connect to the Prima Systems server and update to the latest version,” CISA notes. 

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