Kelihos checks machines' IP addresses against DNS blacklists

Posted by   Virus Bulletin on   Aug 29, 2013

Role of node in a botnet dependent on whether the IP address is blacklisted.

Whenever I look at the results of the VBSpam tests, it always amazes me how large a percentage of spam is blocked because the sending IP address appears on a DNS blacklist.

It is not that I wouldn't expect those that maintain such blacklists not to do a good job: I know that they work hard to keep the lists up to date to block as much spam as possible. But I regularly wonder whether spammers care that most of the emails they send will be blocked by just about any blacklist in existence.

Some spammers apparently do care. In a post for the ZScaler blog, Chris Mannon analyses a recent Kelihos sample that I thought was interesting in this context.

Upon installation on a new machine, the malware queries the machine's public IP address against a number of widely used DNS blacklists. The role the node will play in the botnet then depends on whether or not the IP address is blacklisted: only if it isn't, will the machine be used to send spam.

The blacklisting of IP addresses isn't the only reason why botnet spam - especially when sent from compromised home PCs - is relatively easy to block. Sending spam only from addresses that don't appear on blacklists won't give the spammers a shortcut to users' inboxes - if only because it won't take long before these addresses end up being blacklisted too.

But it does show that cybercriminals haven't given up on spam - and are still actively trying to find ways to get their emails delivered. As can already be seen from some interesting posts on the Malware Must Die blog, despite a number of prominent 'shutdowns', Kelihos is still very much alive and kicking.

Posted on 29 August 2013 by Martijn Grooten

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

VB2018 paper: Lazarus Group: a mahjong game played with different sets of tiles

The Lazarus Group, generally linked to the North Korean government, is one of the most notorious threat groups seen in recent years. At VB2018 ESET researchers Peter Kálnai and Michal Poslušný presented a paper looking at the group's various…

Book your VB2019 ticket now for a chance to win a ticket for BSides London

Virus Bulletin is proud to sponsor this year's BSides London conference, which will take place next week, and we have a number of tickets to give away.

First 11 partners of VB2019 announced

We are excited to announce the first 11 companies to partner with VB2019, whose support will help ensure a great event.

VB2018 paper: Fake News, Inc.

A former reporter by profession, Andrew Brandt's curiosity was piqued when he came across what appeared at first glance to be the website of a small-town newspaper based in Illinois, but under scrutiny, things didn’t add up. At VB2018 he presented a…

Paper: Alternative communication channel over NTP

In a new paper published today, independent researcher Nikolaos Tsapakis writes about the possibilities of malware using NTP as a covert communication channel and how to stop this.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.