If you have an Asus router at the heart of your home network, you may want to check the hard drives of the computers connected to it for a text file called “WARNING_YOU_ARE_VULNERABLE.txt.”

If you see it, it’s because certain Asus models have a vulnerability that exposes a network’s hard drives to the entire Internet. The text file is a public service announcement of sorts, placed by a good Samaritan who’s alerting affected users to the problem.

Be glad it’s only a text file.

Dan Goodin at Ars Technica tells the story of “Jerry”, who found the file on his computer’s hard drive:

“This is an automated message being sent out to everyone effected [sic],” the message, uploaded to his device without any login credentials, read. “Your Asus router (and your documents) can be accessed by anyone in the world with an Internet connection. You need to protect yourself and learn more by reading the following news article: http://nullfluid.com/asusgate.txt.”

Chances are Jerry isn’t alone. A hacker group posted to the Net a list of nearly 13,000 IP addresses of vulnerable Asus routers on the Net, and the Samaritan – who signed the text file with “/g/” – may have dropped it onto any or all of the networks behind those routers.

The flaw was reported to Asus eight months ago, but Goodin reports that researcher Kyle Lovett was told by the company that it wasn’t an issue. Asus apparently patched the flaw last week.

According to the text message left on Jerry’s drive – and Lovett’s own research – the fix is to disable services that allow remote access to the router and the drives behind it, including FTP and Asus’ AICloud. In a second posting, Lovett listed the routers affected:

RT-AC66R Dual-Band Wireless-AC1750 Gigabit Router RT-AC66U Dual-Band Wireless-AC1750 Gigabit Router RT-N66R Dual-Band Wireless-N900 Gigabit Router with 4-Port Ethernet Switch RT-N66U Dual-Band Wireless-N900 Gigabit Router RT-AC56U Dual-Band Wireless-AC1200 Gigabit Router RT-N56R Dual-Band Wireless-AC1200 Gigabit Router RT-N56U Dual-Band Wireless-AC1200 Gigabit Router RT-N14U Wireless-N300 Cloud Router RT-N16 Wireless-N300 Gigabit Router RT-N16R Wireless-N300 Gigabit Router

It has not been a good week for router flaws. On Tuesday, I wrote about a flaw in older Linksys routers currently being exploited by malware that appears to be designed to create a botnet.