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Researchers Help Shut Down Spam Botnet That Enslaved 4,000 Linux Machines (arstechnica.com)
An anonymous reader shares an article on Ars Technica: A botnet that enslaved about 4,000 Linux computers and caused them to blast the Internet with spam for more than a year has finally been shut down. Sophisticated Mumblehard spamming malware flew under the radar for five years. Known as Mumblehard, the botnet was the product of highly skilled developers. It used a custom "packer" to conceal the Perl-based source code that made it run, a backdoor that gave attackers persistent access, and a mail daemon that was able to send large volumes of spam. Command servers that coordinated the compromised machines' operations could also send messages to Spamhaus requesting the delisting of any Mumblehard-based IP addresses that sneaked into the real-time composite blocking list, or CBL, maintained by the anti-spam service. "There was a script automatically monitoring the CBL for the IP addresses of all the spam-bots," researchers from security firm Eset wrote in a blog post published Thursday. "If one was found to be blacklisted, this script requested the delisting of the IP address. Such requests are protected with a CAPTCHA to avoid automation, but OCR (or an external service if OCR didn't work) was used to break the protection."
It used a custom "packer" to conceal the Perl-based source code that made it run...
I think writing it in Perl provides sufficient obfuscation all by itself.
The Eset researchers still aren't certain how Mumblehard is installed. Based on their analysis of the infected server, they suspect the malware may take hold by exploiting vulnerabilities in the Joomla and WordPress content management systems. Their other theory is that the infections are the result of installing pirated versions of the DirecMailer program.
Look for cron jobs executing code from /var/tmp.
They did such a beautiful and informative report(PDF) it's a damn shame not to read it.
Most mainstream distros have some sort of built-in defense against this kind of attack, such as SELinux or AppArmor. Of course, that only works if the Sysadmin has enough sense to let them do their job instead of disabling them to prevent problems that were solved over a decade ago.
Good, inexpensive web hosting
>"There was a script automatically monitoring the CBL for the IP addresses of all the spam-bots, If one was found to be blacklisted, this script requested the delisting of the IP address"
Oooh, that is really clever/evil. And that went on for years and Spamhaus never discovered they were getting automated requests? I would think that would be pretty easy to detect if they get ANOTHER report of spam coming from the same machine and ANOTHER delisting request...
Indeed. And it would help even more if they told us how the machines were infected. As the number is quite low, I expect some configuration mistake that is not commonplace.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Now why am I not shocked these two pieces of spaghetti code were used as an attack vector? It's always important to lock down and isolate each /vhost/ but these who really exemplify why that is so important. Specially WordPress has been one huge security disaster after another.
9/11: Never forget it was a false-flag operation
Loonix is impervious to such things! Teh Open Sores was created by messiah Loonix Toreballs; and as a god, things with his name nevar have problems!
Ah! the troll is strong with this one. These aren't the Linux's you are looking for, move along.
There ain't no such thing as proprietary standards only proprietary formats. Standards are by definition open.