Password-stealing Linux malware served for 3 years and no one noticed


Enlarge / A digital Computer virus.

Getty Pictures | posteriori

A obtain web site surreptitiously served Linux customers malware that stole passwords and different delicate info for greater than three years till it lastly went quiet, researchers mentioned on Tuesday.

The location, freedownloadmanager[.]org, supplied a benign model of a Linux providing often called the Free Obtain Supervisor. Beginning in 2020, the identical area at occasions redirected customers to the area deb.fdmpkg[.]org, which served a malicious model of the app. The model out there on the malicious area contained a script that downloaded two executable information to the /var/tmp/crond and /var/tmp/bs file paths. The script then used the cron job scheduler to trigger the file at /var/tmp/crond to launch each 10 minutes. With that, gadgets that had put in the booby-trapped model of Free Obtain Supervisor have been completely backdoored.

After accessing an IP handle for the malicious area, the backdoor launched a reverse shell that allowed the attackers to remotely management the contaminated gadget. Researchers from Kaspersky, the safety agency that found the malware, then ran the backdoor on a lab gadget to watch the way it behaved.

“This stealer collects knowledge corresponding to system info, searching historical past, saved passwords, cryptocurrency pockets information, in addition to credentials for cloud companies (AWS, Google Cloud, Oracle Cloud Infrastructure, Azure),” the researchers wrote in a report Tuesday. “After gathering info from the contaminated machine, the stealer downloads an uploader binary from the C2 server, saving it to /var/tmp/atd. It then makes use of this binary to add stealer execution outcomes to the attackers’ infrastructure.”

The picture under illustrates the an infection chain.

The infection chain of trojanized versions of Free Download Manager.
Enlarge / The an infection chain of trojanized variations of Free Obtain Supervisor.


After looking out social media posts that mentioned Free Obtain Supervisor, the researchers discovered that some individuals who visited freedownloadmanager[.]org obtained a benign model of the app, whereas others have been redirected to one of many following malicious domains that served the booby-trapped model.

  • 2c9bf1811ff428ef9ec999cc7544b43950947b0f.u.fdmpkg[.]org
  • c6d76b1748b67fbc21ab493281dd1c7a558e3047.u.fdmpkg[.]org
  • 0727bedf5c1f85f58337798a63812aa986448473.u.fdmpkg[.]org
  • c3a05f0dac05669765800471abc1fdaba15e3360.u.fdmpkg[.]org

It’s not clear why some guests obtained the non-malicious model of the software program and others have been redirected to a malicious area. The malicious redirects resulted in 2022 for causes which might be unknown.

The backdoor is an up to date model of malware tracked as Bew, which was printed in 2014. Bew was one of many parts utilized in an assault back in 2017. The stealer known as by the backdoor was installed in a 2019 campaign after first exploiting a vulnerability within the Exim Mail Server.

“Whereas the marketing campaign is at present inactive,” the researchers wrote, referring to the current incident, “this case of Free Obtain Supervisor demonstrates that it may be fairly troublesome to detect ongoing cyber assaults on Linux machines to the bare eye.” They added:

The malware noticed on this marketing campaign has been recognized since 2013. As well as, the implants turned out to be fairly noisy, as demonstrated by a number of posts on social networks. In accordance with our telemetry, victims of this marketing campaign are situated all around the world, together with Brazil, China, Saudi Arabia and Russia. Given these details, it might appear paradoxical that the malicious Free Obtain Supervisor package deal remained undetected for greater than three years.

  • Versus Home windows, Linux malware is rather more not often noticed;
  • Infections with the malicious Debian package deal occurred with a level of chance: some customers obtained the contaminated package deal, whereas others ended up downloading the benign one;
  • Social community customers discussing Free Obtain Supervisor points didn’t suspect that they have been brought on by malware.I

The put up presents quite a lot of file hashes and area and IP addresses that individuals can use to point in the event that they’ve been focused or contaminated within the marketing campaign, which the researchers suspect was a provide chain assault involving the benign model of Free Obtain Supervisor. The researchers mentioned individuals operating the freedownloadmanager[.]org web site didn’t reply to messages notifying them of the marketing campaign. Additionally they didn’t reply to an inquiry for this put up.

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