Security Experts:

Asus Router Flaws Disclosed by Several Researchers

Several security researchers and companies have recently disclosed the details of potentially serious vulnerabilities they discovered in the past months in various Asus routers.

Fortinet reported on Tuesday that its researchers had found a vulnerability in some Asus routers that allows an authenticated attacker to execute arbitrary commands with root privileges.

“Technically, vulnerable models are prone to OS command injections via unsanitized parameters passed to the /apply.cgi,” Fortinet explained. “In Main_Analysis_Content.asp in particular, the SystemCmd variable is created on the client side in the JavaScript function updateOptions(), which in turn uses the values from the input fields pingCNT and destIP. A web proxy can then be used to bypass the local checks that are normally done, and then /cmdRet_check.htm is used to asynchronously return the response from the request. The command is then executed with no further checks performed on the server side.”

Eugene Dokukin, aka “MustLive,” a member of the Ukrainian Cyber Forces activist group, has also disclosed the details of some cross-site scripting (XSS) and cross-site request forgery (CSRF) vulnerabilities affecting several Asus RT-N10 models.Vulnerabilities in Asus routers

Dokukin claimed that the Ukrainian Cyber Forces, who are fighting a cyberwar against the Russian government and separatists in Eastern Ukraine, have exploited these vulnerabilities to take control of devices belonging to their targets.

Researcher Pedro Ribeiro informed Asus of two vulnerabilities via Beyond Security’s SecuriTeam Secure Disclosure program, including access bypass and configuration manipulation issues.

According to Ribeiro, the AsusWRT operating system running on mid-range and high-end Asus routers is affected by vulnerabilities that allow an unauthenticated attacker with access to the local network to remotely execute arbitrary code.

One of the flaws found by the expert allows an attacker to reset the device’s administrator password by sending a specially crafted request. Once the password has been reset, the attacker can log into the web interface with the new password, enable SSH, and then access the device via SSH. Ribeiro also noted that arbitrary command execution is also possible without resetting the admin password.

Finally, Víctor Calvo of Spain-based security firm S2 Grupo, discovered that an attacker can change the credentials of any user, including the device’s administrator, by sending a specially crafted request to the password reset form.

Calvo also found that the Asus AiCloud service, which allows users to remotely access their home network, is affected by XML External Entity (XXE) vulnerabilities that can be exploited to access system files, including ones that store user credentials.

The researchers who identified these vulnerabilities informed Asus of their findings – except for Dokukin, who typically doesn’t inform vendors of the flaws exploited by his group. The company in most cases developed patches within a few weeks after being notified. Information on the latest firmware patches is available on Asus’ Product Security Advisory page.

Related: Asus Settles FTC Charges Over Router Security

Related: Asus Patches Vulnerabilities in RT Routers

Related: CIA Router Hacking Tool Exposed by WikiLeaks

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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.