BKDR_LOWBALL.A
Backdoor.Win32.LowBall (Ikarus)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
Downloaded from the Internet
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It does not have any propagation routine.
It executes commands from a remote malicious user, effectively compromising the affected system.
As of this writing, the said sites are inaccessible.
It gathers information and reports it to its servers.
TECHNICAL DETAILS
20,480 bytes
EXE
Yes
01 Dec 2015
Arrival Details
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Propagation
This backdoor does not have any propagation routine.
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- arbitrary batch scripts
Download Routine
This backdoor accesses the following websites to download files:
- https://api-content.dropbox.com/1/files/auto/{BLOCKED}om
- https://api-content.dropbox.com/1/files/auto/{BLOCKED}om.bat
- https://api-content.dropbox.com/1/{BLOCKED}/{machine name}?overwrite=True
- https://api.dropbox.com/1/{BLOCKED}s/delete
- https://api-content.dropbox.com/1/{BLOCKED}/{machine name}_{file name}
where {file name} can be upload.bat, period.txt, silent.txt
It saves the files it downloads using the following names:
- %User Temp%\WmiApCom
- %User Temp%\WmiApCom.bat
- %User Temp%\onlineflagfile
- %User Temp%\upload
- %User Temp%\upload.bat
- %User Temp%\download
- %User Temp%\period.txt
- %User Temp%\silent.txt
(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.)
As of this writing, the said sites are inaccessible.
Other Details
This backdoor gathers the following information and reports it to its servers:
- machine name
- information obtainable via batch script
NOTES:
This backdoor uses a legitimate cloud-storage service to act as the C&C server.
It uses the Dropbox API with the following hard-coded bearer access token:
Authorization: Bearer sgKddaX_ntAAAAAAAAAADVYeex9Pc0NuhGII10uLUhy-Kte7gEehQSxjYgRB2yWT
It must be executed with "-st" as its parameter to start its backdoor routine.
SOLUTION
9.800
12.196.05
07 Dec 2015
12.197.00
08 Dec 2015
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
Restart in Safe Mode
Step 4
Search and delete these files
- %User Temp%\WmiApCom
- %User Temp%\WmiApCom.bat
- %User Temp%\onlineflagfile
- %User Temp%\upload
- %User Temp%\upload.bat
- %User Temp%\download
- %User Temp%\period.txt
- %User Temp%\silent.txt
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_LOWBALL.A. 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
Scan your computer with your Trend Micro product to delete files detected as BKDR_LOWBALL.A. 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.
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