Security Experts:

Backdoor Found in Several Fortinet Products

FortiOS is not the only Fortinet product affected by the backdoor whose existence was brought to light earlier this month, a review conducted by the company has shown.

On January 9, someone published on the Full Disclosure mailing list an exploit for an SSH backdoor affecting older versions of FortiOS, the hardened operating system running on Fortinet’s FortiGate firewall platform.

Fortinet, which claimed the issue was a management authentication bug and not a malicious backdoor, said the critical vulnerability was silently fixed in July 2014 with the release of FortiOS 4.3.17 and 5.0.8.

After the vulnerability was publicly disclosed, Fortinet’s security, engineering and QA teams conducted a review of all the company’s products and determined that the issue has also affected some versions of FortiSwitch switches, FortiAnalyzer centralized log and reporting appliances, and FortiCache web caching appliances.

The security bug can be exploited to log in to vulnerable devices with admin privileges via SSH in Interactive-Keyboard mode using a password that is shared across all devices. Access is granted only if the “Administrative Access” feature is enabled for SSH.

According to an advisory published by the company, the vulnerability affects devices running FortiAnalyzer 5.0.5 through 5.0.11 and 5.2.0 through 5.2.4, FortiSwitch 3.3.0 through 3.3.2, and FortiCache 3.0.0 through 3.0.7. The flaw was addressed last week with the release of FortiAnalyzer 5.0.12 and 5.2.5, FortiSwitch 3.3.3 and FortiCache 3.0.8.

The company has pointed out that the 4.3 branch of FortiAnalyzer and the 3.1 branch of FortiCache are not impacted. The updates made available by Fortinet also cover end-of-life and legacy products. Customers who cannot install the patches can apply workarounds recommended by the vendor for each of the affected products.

The SANS Institute's Internet Storm Center (ISC) reported that unknown actors have been scanning the Web in search for vulnerable devices

“As previously stated, this vulnerability is an unintentional consequence of a feature that was designed with the intent of providing seamless access from an authorized FortiManager to registered FortiGate devices. It is important to note, this is not a case of a malicious backdoor implemented to grant unauthorized user access,” Fortinet explained in a blog post.

Several experts who have analyzed the Fortinet backdoor agree that it seems to be a problematic appliance management mechanism and not a malicious backdoor such as the one found in Juniper Networks’ ScreenOS firewall operating system.

The backdoor in ScreenOS was introduced by a third-party that Juniper is still trying to identify. Some have pointed the finger at the United States National Security Agency (NSA), which is known to have targeted Juniper Networks products in the past, but officials have expressed concern that a foreign government might be behind the incident.

*Updated with information from ISC

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.