A previously discovered security vulnerability found in multiple router models and then quickly patched, may not have been as effective as early reported. According to the security researcher who first discovered the vulnerability, the patch seems to only hide the router backdoor and does nothing to close the hole it creates.
The original (and still active) vulnerability
In December 2013, the security researcher Eloi Vanderbeken discovered a previously undocumented backdoor in many popular wireless router models, such as Belkin, Cisco, and Netgear. The backdoor allowed an attacker to gain administrative access remotely.
Other security researchers rapidly confirmed the discovery by Vanderbeken and then by the following month a patch was released to close the backdoor on all affected routers.
Until recently, the patch was believed to have repaired the hole created by the backdoor until Vanderbeken began checking the status of the patch. What he discovered suggests that the vulnerability might not have been an accident.
The backdoor patch has a backdoor
In the recently published online slides, Vanderbeken suggests that the original backdoor was not an unintentional bug, but more likely a feature. He reports that the patch, meant to repair and close the backdoor administrative access, only hides the backdoor and requires a simple process to regain access. This fact is what leads Vanderbeken to believe that the backdoor was intentional created and not accidental.
Currently, the full extent of the backdoor's backdoor is unknown. Vanderbeken tested his hypothesis on a single Netgear router (DGN1000), but published his process so that others may test the functionality of different router model's patching.