Over 200,000 DrayTek routers vulnerable to total device takeover

Over 200,000 routers made by DrayTek are subject to a serious vulnerability, which could open companies up to network breaches.

The DrayTek Vigor 3910 is currently vulnerable to complete compromise by threat actors and is particularly at risk if it has an internet-facing management interface.

Researchers from cybersecurity firm Trellix identified the vulnerability within the model in a blog post, as well as within 28 other devices from DrayTek that share the same code base. They stressed that at present, there are no examples of threat actors in the wild using the vulnerability.

The researchers have warned companies that once routers are compromised, they leave a network open to malicious action such as intellectual property theft, stolen passwords, data breaches, or a ransomware attack.

DrayTek is a Taiwanese manufacturer of routers that cater to so-called ‘SoHo’ small and medium businesses (SMBs), with their products often used to provide remote-working employees with virtual private network (VPN) access.

Because of a logic bug in its code, threat actors can exploit the management interface of the affected routers by inputting a base64 encoded string as username and password when prompted. This causes a buffer overflow on its login page, allowing a takeover of the router’s ‘DrayOS’.

The attack can be undertaken over the router’s local area network (LAN). If the management interface of the router is configured to be internet facing, the attack can be carried out remotely over the internet.

Researchers have issued several recommendations, including keeping firmware up-to-date, preventing the management interface from being exposed to the internet if possible, and changing the password to any affected devices.

The vulnerability has been filed under CVE-2022-32548 and Trelix was quick to praise DrayTek for releasing a firmware patch within 30 days of being made aware of the issue.

“A firewall or other piecemeal cybersecurity tool is not a cybersecurity strategy. Small businesses must not underestimate their value to an attacker and adopt a mindset and strategy centred on when they will be targeted versus if," commented Philippe Laulheret, senior security researcher at Trellix.

"SMBs can't underestimate the value of their data and IP, or the potential for their edge devices to be leveraged in botnet attack, or even the risk of becoming a steppingstone for attackers to compromise SMBs' customer networks.”