RANSOM_CERBER.SA
Ransom:Win32/Cerber (Microsoft); Win32/Filecoder.Cerber.B trojan (NOD32)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It deletes the initially executed copy of itself. It is capable of encrypting files in the affected system.
TECHNICAL DETAILS
495,749 bytes
EXE
Yes
06 Oct 2016
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Installation
This Trojan drops the following files:
- %User Temp%\tmp8D.bmp - background image
- {folders containing encrypted files}\README.hta - Ransom Note
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Other System Modifications
This Trojan changes the desktop wallpaper by modifying the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\tmp8D.bmp
Other Details
This Trojan renames encrypted files using the following names:
- {10 Random Characters}.{4 Random Characters}
It does the following:
- It deletes all shadow copies by executing the following command:
- WMIC.exe shadowcopy delete
- It sends out UDP packets via port 6892 that may flood subnets.
It deletes the initially executed copy of itself
It is capable of encrypting files in the affected system.
SOLUTION
9.800
12.820.05
06 Oct 2016
12.821.00
07 Oct 2016
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 3
Delete this registry value
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Control Panel\Desktop
- Wallpaper = %User Temp%\tmp8D.bmp
- Wallpaper = %User Temp%\tmp8D.bmp
Step 4
Search and delete these files
- {folders containing encrypted files}\README.hta
- %User Temp%\tmp8D.bmp
Step 5
Scan your computer with your Trend Micro product to delete files detected as RANSOM_CERBER.SA. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.
Step 6
Reset your Desktop properties
Step 7
Restore encrypted files from backup.
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