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AsusWRT LAN Unauthenticated Remote Code Execution

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AsusWRT LAN Unauthenticated Remote Code Execution

Disclosed
01/22/2018
Created
06/14/2018

Description

The HTTP server in AsusWRT has a flaw where it allows an unauthenticated client to perform a POST in certain cases. This can be combined with another vulnerability in the VPN configuration upload routine that sets NVRAM configuration variables directly from the POST request to enable a special command mode. This command mode can then be abused by sending a UDP packet to infosvr, which is running on port UDP 9999 to directly execute commands as root. This exploit leverages that to start telnetd in a random port, and then connects to it. It has been tested with the RT-AC68U running AsusWRT Version 3.0.0.4.380.7743.

Author(s)

  • Pedro Ribeiro <pedrib@gmail.com>

Platform

Unix

Architectures

cmd

Development

References

Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':

msf > use exploit/linux/http/asuswrt_lan_rce
msf exploit(asuswrt_lan_rce) > show targets
    ...targets...
msf exploit(asuswrt_lan_rce) > set TARGET < target-id >
msf exploit(asuswrt_lan_rce) > show options
    ...show and set options...
msf exploit(asuswrt_lan_rce) > exploit

Time is precious, so I don’t want to do something manually that I can automate. Leveraging the Metasploit Framework when automating any task keeps us from having to re-create the wheel as we can use the existing libraries and focus our efforts where it matters.

– Jim O’Gorman | President, Offensive Security

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