TROJ_BRANTALL.A
TrojanDownloader:Win32/Brantall.C (Microsoft); InstallBrain (fs) (Sunbelt); Trojan horse Downloader.Generic13.BRPE (AVG)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
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 executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
TECHNICAL DETAILS
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 component file(s):
- %User Temp%\{random number}.bat - used to delete the dropped copy
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It drops the following copies of itself into the affected system:
- %User Temp%\{random number}.exe - deleted afterwards
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
Download Routine
This Trojan accesses the following websites to download files:
- http://{BLOCKED}ap1-639932975.us-east-1.elb.{BLOCKED}onaws.com/installer/{BLOCKED}rap.php?cmp=40&sub=3515&rkey=%7BFE6E631B-5278-469E-858B-ACCBCBA3B919%7D
It saves the files it downloads using the following names:
- %User Temp%\component_{number}
- User Temp%\component_{number}.decrypt
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
NOTES:
However, as of this writing, backend server is at capacity.
TROJ_BRANTALL is known to download the BKDR_MEVADE malware family.
SOLUTION
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
Identify and terminate files detected as TROJ_BRANTALL.A
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
Step 3
Search and delete this file
- %User Temp%\component_{number}
- %User Temp%\component_{number}.decrypt
- %User Temp%\{random number}.exe
- %User Temp%\{random number}.bat
Step 4
Scan your computer with your Trend Micro product to delete files detected as TROJ_BRANTALL.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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