Research > Zero-Day Tracker > 20131012
Multiple Routers (D-Link/Planex) Coded Backdoor
See D-Link Advisory for more details.
Multiple routers from D-Link and Planex share firmware code, which contains a backdoor that has been hardcoded into the firmware. The firmware contains an authentication routine that is bypassed when a user-agent, "xmlset_roodkcableoj28840ybtide", makes a request. This allows an attacker to manipulate the router at will, if they change their user-agent to "xmlset_roodkcableoj28840ybtide". Additionally, this backdoor makes a stack-based overflow available to a remote attacker, which may allow an attacker to arbitrarily execute code on the router.
Authentication Bypass/Remote Code Execution
Remote attackers may be able to modify settings on vulnerable routers by changing their user-agents to "xmlset_roodkcableoj28840ybtide", which bypasses authentication. Additionally, a proof of concept has been released that demonstrates the availability of a vulnerability exposed by the authentication bypass, that allows for remote code execution within an affected router. This may allow a remote attacker to re-write the firmware of a vulnerable router, allowing an attacker to re-route traffic or perform other malicious actions on a vulnerable device.
See D-Link Advisory for more details regarding patched D-Link firmwares.
BeyondTrust's Retina® Network Security Scanner scans devices to detect for this vulnerability.
31467 - Multiple Routers Hardcoded Backdoor (20131012) - Remote
2013-10-12 - Original research/advisory released.
Copyright ©1998-2011 eEye Digital Security
Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please email alert@eEye.com for permission.
The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are no warranties, implied or express, with regard to this information. In no event shall the author be liable for any direct or indirect damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk.