Parite.BKR: A Backdoor Uses Image File to avoid detection.

September 2, 2015

The Dell Sonicwall Threats Research team observed reports of a New Malware family named GAV: Parite.BKR actively spreading in the wild. This time attacker uses an Encrypted JPG Image File to avoid detection by Anti-Virus programs.

Infection Cycle:

The Malware uses the following icon:


  • a168e4773236bf97e9920a3c2e280e4c

The Malware adds the following files to the system:

  • Malware.exe

  • %Userprofile%Local SettingsTempllg3AC.tmp [Detected as GAV: Parite.BKR (Trojan)]

    • %Userprofile%Local SettingsTemporary Internet FilesContent.IE5YGPZUUH84[1].jpg [ Encrypted JPG]

    • C:Program FilesAppPatch4.dll [ Encrypted JPG]

    • C:Program FilesMicrosoft GvumyzPbvwlsu.exe [Decrypted EXE ]

The Malware adds the following keys to the Windows registry to ensure persistence upon reboot:

  • HKLMSOFTWAREMicrosoftWindowsCurrentVersionRunWsiswy woogmoag

    • C:Program FilesMicrosoft GvumyzPbvwlsu.exe

Once the computer is compromised, the malware copies its own executable file to Program files folder.

The file Pbvwlsu.exe is dropped after malware launches on the target system, the malware tries to download JPG encrypted file from its own C&C server from following domain:

Here is an example of encrypted JPG file:

The Malware injects Explorer.exe to infect executable files on the local file system and on network shares. Here is an example of the Malware injection:

When the Malware injects Explorer.exe its opens a Backdoor on the targets Machine on UDP Port 30167, here is an example:

Command and Control (C&C) Traffic

Parite.BKR performs C&C communication over 80 ports. The malware retrieves some files from its own C&C server via following format, here are some examples:

We have been monitoring varying hits over the past few days for the signature that blocks this threat:

SonicWALL Gateway AntiVirus provides protection against this threat via the following signature:

  • GAV: Parite.BKR (Trojan)