Botnet Seized by Agencies

Tuesday, December 8, 2015 @ 05:12 PM gHale

One of the most widely distributed malware families, the Dorkbot botnet, fell into the hands of global law enforcement agencies in partnership with Microsoft, ESET and CERT Polska.

The malware, also known as Nrgbot, has infiltrated over a million computers in 190 countries by spreading through multiple channels, including USB flash drives, instant messaging programs, social networking sites, exploit kits, and spam emails.

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As soon the malware infects a machine, it steals user’s personal information and credentials, disables security protection, and distributes other forms of malware.

The Internet Relay Chat (ICR) based malware steals passwords for popular services, including Facebook and Twitter, connects to an IRC server to receive further commands, and can also install code from malware families such as Win32/Kasidet, aka Neutrino bot, used to launch DDoS attacks, and Win32/Lethic, a spam bot.

On infected systems, Dorkbot searches for removable media to replicate itself, and places two types of files on them, namely a dropper and .LNK files with enticing names that point to it. The dropper (Win32/Dorkbot.I) contacts a hardcoded C&C server to download a file that will decrypt and execute a wrapper (Win32/Dorkbot.L) used to install the main malware component.

It launches the main Dorkbot IRC component (Win32/Dorkbot.B) and hooks into the DnsQuery API, as the main component does not contain the true C&C domains. The IRC and the wrapper try to resolve domains, which makes it difficult to obtain the real C&C addresses, said researchers at security firm, ESET in a blog post. However, as soon as the installation is completed, the system connects to the IRC server and waits for commands.

Although it has been around, Dorkbot is still prevalent, ESET researchers said, explaining they find fresh samples every day from all around the world. The malware features a modular design and has managed to reinvent itself through the years, researchers said.

Microsoft said its security tools have detected Dorkbot on an average of 100,000 infected machines per month for the past six months. The company also said Microsoft Malware Protection Center (MMPC) has been monitoring the malware since April 2011, and users in 10 countries have felt the impact over the past six months, accounting for 61 percent of the infections.

Security products out there can detect and block Dorkbot, and users should keep their antivirus programs updated at all times to ensure protection. Additionally, users should be cautious when opening emails or social media messages from unknown users and when downloading software from third-party websites.