this post was submitted on 12 Sep 2023
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A reported Free Download Manager supply chain attack redirected Linux users to a malicious Debian package repository that installed information-stealing malware.

The malware used in this campaign establishes a reverse shell to a C2 server and installs a Bash stealer that collects user data and account credentials.

Kaspersky discovered the potential supply chain compromise case while investigating suspicious domains, finding that the campaign has been underway for over three years.

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[–] [email protected] 211 points 1 year ago (9 children)

Now I need to know who the hell has installed Free Download Manager on Linux.

[–] [email protected] 43 points 1 year ago (1 children)

And via a website too. That's like pushing a car. One of the main strengths of Linux are open repositories, maintained by reputable sources and checked by thousands of reputable people. Packages are checksummed and therefore unable to be switched by malicious parties. Even the AUR is arguably a safer and more regulated source. And it's actually in there.

[–] [email protected] 51 points 1 year ago (1 children)

And via a website too

Everyone knows real admins do curl https://raw.githubusercontent.com/something/or/other/install.sh | sudo bash

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[–] [email protected] 21 points 1 year ago (1 children)

The same people that would have given that poor nigerian prince their bank account details

[–] [email protected] 11 points 1 year ago (5 children)

It's still my favorite download manager on Windows. It often downloads file significantly faster than the download manager built into browsers. Luckily I never installed it on Linux, since I have a habit of only installing from package managers.

Do you know of a good download manager for Linux?

[–] [email protected] 14 points 1 year ago (3 children)

How much faster are we talking?

I’ve honestly never looked at my downloads and though huh you should be quicker, well maybe in 90’s.

[–] [email protected] 7 points 1 year ago

Right? I've not thought about download speeds since the 2000's.

[–] [email protected] 7 points 1 year ago (2 children)

FDM does some clever things to boost download speeds. It splits up a download into different chuncks, and somehow downloads them concurrently. It makes a big difference for large files (for example, Linux ISOs).

[–] [email protected] 7 points 1 year ago (1 children)

Im curious as to how it would achieve that?

It can’t split a file before it has the file. And all downloads are split up. They’re called packets.

Not saying it doesn’t do it, just wondering how.

[–] [email protected] 13 points 1 year ago (1 children)

It could make multiple requests to the server, asking each request to resume starting at a certain byte.

[–] [email protected] 5 points 1 year ago (1 children)

Interesting.

I feel I’ll save this rabbit hole for weekend and go and have a look at what they do.

[–] [email protected] 18 points 1 year ago (1 children)

The key thing to know is that a client can do an HTTP HEAD request to get just the Content-Length of the file, and then perform GET requests with the Range request header to fetch a specific chunk of a file.

This mechanism was introduced in HTTP 1.1 (byte-serving).

[–] [email protected] 5 points 1 year ago

Huh.. that’s super interesting and thanks for sharing.

[–] [email protected] 6 points 1 year ago (1 children)

just grabbed a gig file - it would take about 8 minutes with a standard download in Firefox. Use a manager or axel and it will be 30 seconds. Then again speed isnt everything, its also nice to be able to have auto retry and completion.

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[–] [email protected] 8 points 1 year ago (1 children)

JDownloader, XDM, FileCentipede (this one is the closest to IDM, although it uses closed source libraries), kGet, etc.

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[–] [email protected] 4 points 1 year ago (1 children)

axel. use axel -n8 to make 8 connections/segments which it will assemble when it is done

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[–] [email protected] 10 points 1 year ago

Gotta admit, it was me. I've only used a computer for short time.
I've got my first laptop 3 years ago, and that broke after just 2 months. And anyway, with AMD Athlon 64 it greatly struggled with a browser. So really I only started seriously using computer at the start of 2021, when I got another, usable laptop. And that's when I downloaded freedownloadmanager.deb. Thankfully, I didn't get that redirect, so it was a legitimate file.

[–] [email protected] 8 points 1 year ago

Oh, I know someone who adds the word “free” to various search words like “free pdf reader” or “free flash player” (happened a very long time ago). He’s also the kind of person who I can imagine having a bunch of viruses and malware on his computer.

[–] [email protected] 5 points 1 year ago

People not well versed in Linux.

You know, the non-techies, which the Linux community claims should know such things but obviously does not.

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[–] [email protected] 56 points 1 year ago (1 children)

The article mentions how to check for infection:

If you have installed the Linux version of the Free Download Manager between 2020 and 2022, you should check and see if the malicious version was installed.

To do this, look for the following files dropped by the malware, and if found, delete them:

/etc/cron.d/collect
/var/tmp/crond
/var/tmp/bs
[–] [email protected] 7 points 1 year ago

Also you can check the .deb file's postinst script. If it looks like shown here, no bueno.

[–] [email protected] 38 points 1 year ago (5 children)

"Non-free download manager"

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[–] [email protected] 34 points 1 year ago (3 children)

What is a free download manager and why would someone need one?

[–] [email protected] 23 points 1 year ago (1 children)

Back in the day when most stuff was on FTP and HTTP and your connection was crap and could drop at any time, you'd use a download manager to smooth things along. It could resume downloads when connection dropped, it could keep a download going for days on end and resume as needed, and it could abusing the bandwitdh limitations of the source site by using multiple parallel connections that pulled on different file chunks. In some ways it was very similar to how we use BT today.

It was also useful to keep a history of stuff you'd downloaded in case you needed it again, manage the associated files etc.

[–] [email protected] 16 points 1 year ago

and it could abusing the bandwitdh limitations of the source site by using multiple parallel connections that pulled on different file chunks

Also for files which had multiple different mirror sites you could download chunks from multiple mirrors concurrently which would allow you to max out your bandwidth even if individual mirrors were limiting download speeds.

[–] [email protected] 14 points 1 year ago (1 children)

It's a download client that can pause/Resume downloads, as well as use multiple connections to download files

[–] [email protected] 4 points 1 year ago (2 children)

Like a BitTorrent?

I guess I just don't download that much stuff.

[–] [email protected] 10 points 1 year ago

Sucks having your connection drop and having to redlownload the entire thing again. Managers are a fix.

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[–] [email protected] 6 points 1 year ago* (last edited 1 year ago)

Back in the 2000s, browsers were really bad at downloading big things over slow connections since they couldn't resume, a brief disconnect could destroy hours of progress. But I don't think you need this anymore.

[–] [email protected] 25 points 1 year ago (2 children)

How is it possible that users noticed strange behaviors (new Cron jobs) and they didn't check the script launched by those jobs 😱

[–] [email protected] 66 points 1 year ago (2 children)

Linux popularity going up means the percentage of users who know what cron is goes down.

[–] [email protected] 26 points 1 year ago (2 children)

Is Disney finally making Tron sequel?

[–] [email protected] 15 points 1 year ago (1 children)

No it’s a disease that makes you poop a lot

[–] [email protected] 9 points 1 year ago (4 children)

No that's Crohn's, cron is a type of headwear for monarchs

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[–] [email protected] 5 points 1 year ago* (last edited 1 year ago)

They actually are, kind of. It's called Tron: Ares and it's been in production hell for some years, the most recent delay being due to the ongoing writer's strike. Filming is expected to start after the strike is over, but personally my enthusiasm for the movie died after they announced Jared Leto as one of the cast.

[–] [email protected] 7 points 1 year ago* (last edited 1 year ago)

If they were complaining about cronjobs being created (like the post says), then they must have known what cron is.

[–] [email protected] 17 points 1 year ago (1 children)

Idk if I'd check crontab regularly.

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[–] [email protected] 22 points 1 year ago (2 children)

Finally linux is getting popular enough to make viruses. Yay?. Insert gru meme here

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[–] [email protected] 8 points 1 year ago (1 children)

malicious Debian package repository

*laughs in RPM*

This comment was presented by the fedora gang.

[–] [email protected] 13 points 1 year ago (1 children)

Right, but you could do the same with RPM. Not everyone is aware of this, but installing a package executes scripts with root access over your system.

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[–] [email protected] 8 points 1 year ago* (last edited 1 year ago) (1 children)

Mmmh. You kinda deserve being infected if you do things like this. Every beginner tutorial specifically tells you not to download random stuff from the internet and 'sudo' install it. Every Wiki with helpful information has these boxes that tell you not to do it. I'm okay if you do it anyways. But don't blame anyone else for the consequences. And don't tell me you haven't been warned.

Also I wonder about the impact this had. It went unnoticed for 3 years. So I can't imagine it having affected many people. The text says it affected few people. And it didn't have any real impact.

But supply chain attacks are real. Don't get fooled. And don't install random stuff. Install the download manager from your package repository instead.

[–] [email protected] 8 points 1 year ago (1 children)

I kind of disagree. Applications often require root permissions to install themselves, since regular users can't access certain folders like /opt, etc.

Also, do you really think that people would actually read the source and then compile all their software themselves? Do you do the same?

Generally though I do agree, you're probably fine installing software from your distro's repos but even that's not bulletproof and also it's not like third-party repos are uncommon either.

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[–] [email protected] 6 points 1 year ago (1 children)

I had to essentially read the same thing four times before there was any new information in this post. Not sure if that's a Jerboa thing or what, but probably could have been avoided.

[–] [email protected] 8 points 1 year ago

Yeah I agree, sorry about that. I thought that the body-text field was mandatory to fill in, so I used the introductory paragraph from the article so as not to editorialize.

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