Feeds

New trojan in mass DNS hijack

Single box pollutes entire LAN

Providing a secure and efficient Helpdesk

Researchers have identified a new trojan that can tamper with a wide array of devices on a local network, an exploit that sends them to impostor websites even if they are hardened machines that are fully patched or run non-Windows operating systems.

The malware is a new variant of the DNSChanger, a trojan that has long been known to change the domain name system settings of PCs and Macs alike. According to researchers with anti-virus provider McAfee's Avert Labs, the update allows a single infected machine to pollute the DNS settings of potentially hundreds of other devices running on the same local area network by undermining its dynamic host configuration protocol, or DHCP, which dynamically allocates IP addresses.

"Systems that are not infected with the malware can still have the payload of communicating with the rogue DNS servers delivered to them," McAfee's Craig Schmugar writes here of the new variant. "This is achieved without exploiting any security vulnerability."

The scenario plays out something like this:

  • Jill connects a PC infected by the new DNSChanger variant to a coffee shop's WiFi hotspot or her employer's local network.
  • Steve connects to the same network using a fully-patched Linux box, which requests an IP address.
  • Jill's PC injects a DHCP offer command to instruct Steve's computer to rout all DNS requests through a booby-trapped DNS server.
  • Steve's Linux box can no longer be trusted to visit authoritative websites. Although the address bar on his browser may show he is accessing bankofamerica.com, he may in fact be at an impostor website.

The only way a user might know the attack is underway is by manually checking the DNS server his computer is using (e.g. by typing "ipconfig /all" at a Windows command prompt). There are several countermeasures users can take, Schmugar said, the easiest being hard-coding a DNS server in a machine's configuration settings.

(In Windows, this can be done by going to Start > Control Panel > Network Connections and right clicking on Local Area Connection and choosing properties. Scroll down to Internet Protocol (TCP/IP) and click the Properties button. Then type in the primary and secondary for your DNS service. We're partial to OpenDNS, whose settings are 208.67.222.222 and 208.67.220.220.)

In an interview, Schmugar said the DHCP attack doesn't exploit a vulnerability in either user machines or network hardware, allowing it to work with a wide variety of home and enterprise routers. It involves a ndisprot.sys driver that is installed on the infected box. Once there, it monitors network traffic for DHCP requests and responds with bogus offers that contain the IP address to the rogue DNS server.

DNSChanger has already been viewed exploiting router weaknesses to change DNS settings, but the ability to poison other machine's DHCP connections appears to be new, said Eric Sites, VP of research at Sunbelt Software. For the moment, the new variant doesn't appear to be widely circulated, but the prospect of a trojan that can poison other machines' DHCP connections suggests this one is worth watching. ®

Choosing a cloud hosting partner with confidence

More from The Register

next story
SMASH the Bash bug! Apple and Red Hat scramble for patch batches
'Applying multiple security updates is extremely difficult'
Shellshock: 'Larger scale attack' on its way, warn securo-bods
Not just web servers under threat - though TENS of THOUSANDS have been hit
Apple's new iPhone 6 vulnerable to last year's TouchID fingerprint hack
But unsophisticated thieves need not attempt this trick
Hackers thrash Bash Shellshock bug: World races to cover hole
Update your gear now to avoid early attacks hitting the web
Oracle SHELLSHOCKER - data titan lists unpatchables
Database kingpin lists 32 products that can't be patched (yet) as GNU fixes second vuln
Who.is does the Harlem Shake
Blame it on LOLing XSS terroristas
Researchers tell black hats: 'YOU'RE SOOO PREDICTABLE'
Want to register that domain? We're way ahead of you.
Stunned by Shellshock Bash bug? Patch all you can – or be punished
UK data watchdog rolls up its sleeves, polishes truncheon
prev story

Whitepapers

A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.