Security News > 2022 > May > Unpatched DNS Bug Puts Millions of Routers, IoT Devices at Risk

An unpatched Domain Name System bug in a popular standard C library can allow attackers to mount DNS poisoning attacks against millions of IoT devices and routers to potentially take control of them, researchers have found.

"The flaw is caused by the predictability of transaction IDs included in the DNS requests generated by the library, which may allow attackers to perform DNS poisoning attacks against the target device," Nozomi's Giannis Tsaraias and Andrea Palanca wrote in the post.

In a DNS poisoning attack- also known as DNS spoofing and DNS cache poisoning-an attacker deceives a DNS client into accepting a forged response.

Though it affects a different set of targets, the DNS flaw also has a broad scope not only because of the devices it potentially affects, but also because of the inherent importance of DNS to any device connecting over IP, researchers said.

This predictability creates a scenario in which an an attacker would need to craft a DNS response that contains the correct source port, as well as win the race against the legitimate DNS response incoming from the DNS server to exploit the flaw, researchers said.

To exploit the flaw also depends on how an OS applies randomization of source port, which means an attacker would have to bruteforce the 16-bit source port value by sending multiple DNS responses, while simultaneously beating the legitimate DNS response, researchers added.

News URL

https://threatpost.com/dns-bug-millions-routers-iot-risk/179478/