BKDR_DORIFEL.AE
VirTool:Win32/Obfuscator.ADH (Microsoft), PWS-Zbot-FASW!8C9349562076 (McAfee), W32/Dorifel.ACTZ!tr (Fortinet), Trojan.Win32.Bublik (Ikarus), Win32/Kryptik.AXXZ trojan (ESET)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
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 executes then deletes itself afterward.
TECHNICAL DETAILS
50,176 bytes
EXE
Yes
03 Apr 2013
Downloads files, Compromises system security
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.
Installation
This backdoor executes then deletes itself afterward.
It injects threads into the following normal process(es):
- svchost.exe
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MSConfig = ""%User Profile%\{Random File Name}.exe""
Backdoor Routine
This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}.{BLOCKED}.99.250.178/daol/asidfk11.dat?wv=51&bt=32
NOTES:
It downloads a JPG file from the following link:
- http://{BLOCKED}report.com/images/2009/05/naughty-elephant.jpg
It then saves and open it as follows:
- %Current Folder%\{Malware Name}.jpg
This is done to trick users into thinking that the executed file is legitimate.
It then connects to the following URL to download a file MeNakedTIFF.exe:
- http://{BLOCKED}.{BLOCKED}.99.250.178/daol/oadl.php
It saves a copy of the downloaded file as %User Profile%\{Random File Name}.exe and execute it. Trend Micro also detects the downloaded file as BKDR_DORIFEL.AE.
This backdoor may compose messages that can be part of its spamming routine. It uses any of the following Simple Mail Transfer Protocol (SMTP) servers to send its messages:
- 207.46.100.11
- 66.196.118.35
- aspmx.l.google.com
- mxs.mail.ru
- alt1.aspmx.l.google.com
- alt2.aspmx.l.google.com
SOLUTION
9.300
9.834.02
03 Apr 2013
9.835.00
04 Apr 2013
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
Scan your computer with your Trend Micro product and note files detected as BKDR_DORIFEL.AE
Step 3
Restart in Safe Mode
Step 4
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\Software\Microsoft\Windows\CurrentVersion\Run
- MSConfig = ""%User Profile%\{Random File Name}.exe""
- MSConfig = ""%User Profile%\{Random File Name}.exe""
Step 5
Search and delete this file
- %Current Folder%\{Malware Name}.jpg
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_DORIFEL.AE. 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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