BKDR_SIMDA.OFP
Backdoor:Win32/Simda (Microsoft), Backdoor.Win32.Simda.b (Sunbelt), W32/Simda.B!tr (Fortinet), Backdoor.Win32.Simda (Ikarus)
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 commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.
As of this writing, the said sites are inaccessible.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
549,888 bytes
EXE
Yes
05 May 2013
Connects to URLs/IPs, Compromises system security, Downloads files
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 drops the following files:
- %Application Data%\{random name}.reg
- %Application Data%\mcp.ico
- %Desktop%\Computer.lnk
- %User Temp%\{random name}.sys
- %User Temp%\{random number}.tmp
- %User Temp%\{random name}.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.. %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:
- %Application Data%\ScanDisc.exe
- %Application Data%\{random name}.exe
- %User Temp%\{random number}.tmp
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %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.)
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\RunOnce
{random name} = "%Application Data%\{random name}.exe"
Other System Modifications
This backdoor adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
ConsentPromptBehaviorAdmin = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
ConsentPromptBehaviorUser = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows
update = "shortcut"
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Download and execute arbitrary files
- Remote shell
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}.{BLOCKED}.243.64/chrome/report.html
- http://{BLOCKED}.{BLOCKED}.12.201
- http://{BLOCKED}.{BLOCKED}.83.117
- http://{BLOCKED}.{BLOCKED}.38.173
- update.{pseudorandom}.com
- report.{pseudorandom}.com
- http://{BLOCKED}.{BLOCKED}.216.6
It posts the following information to its command and control (C&C) server:
- OS information
- Drive information
However, as of this writing, the said sites are inaccessible.
Download Routine
This backdoor accesses the following websites to download files:
- http://{BLOCKED}1.{BLOCKED}string.com/?abbr=RTK&setupType=update&uid={random number}&ttl={random string}&controller=microinstaller&pid=3
- http://{BLOCKED}1.{BLOCKED}string.com/update_c1eec.exe
- http://{BLOCKED}1.{BLOCKED}main.com/?abbr=RTK&action=download&setupType=umx&setupFileName=process_64.exe
- http://{BLOCKED}1.{BLOCKED}string.com/?controller=hash
It saves the files it downloads using the following names:
- %User Temp%\{random number}.exe
- %System Root%\text.exe
(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.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
As of this writing, the said sites are inaccessible.
HOSTS File Modification
This backdoor modifies the system's HOSTS files to redirect users once the following Web site(s) are accessed:
- www.google-analytics.com
- ad-emea.doubleclick.net
- www.statcounter.com
Other Details
This backdoor checks for the presence of the following process(es):
- Aircrack-ng Gui.exe
- apis32.exe
- CamRecorder.exe
- CamtasiaStudio.exe
- cv.exe
- DrvLoader.exe
- dumpcap.exe
- ERDNT.exe
- ERUNT.exe
- EtherD.exe
- irise.exe
- IrisSvc.exe
- observer.exe
- ollydbg.exe
- PEBrowseDbg.exe
- Regshot.exe
- SandboxieDcomLaunch.exe
- SandboxieRpcSs.exe
- SbieCtrl.exe
- SbieSvc.exe
- Sniffer.exe
- SUPERAntiSpyware.exe
- SymRecv.exe
- Syser.exe
- tcpdump.exe
- VBoxService.exe
- VBoxTray.exe
- windbg.exe
- WinDump.exe
- wireshark.exe
- wspass.exe
- ZxSniffer.exe
It deletes the initially executed copy of itself
NOTES:
It checks for the following registry keys:
AppEvents\Schemes\Apps\Bopup Observer
SOFTWARE\APIS32
Software\B Labs\Bopup Observer
Software\Classes\*\shell\sandbox
Software\Classes\Folder\shell\sandbox
SOFTWARE\Classes\PEBrowseDotNETProfiler.DotNETProfiler
SOFTWARE\Classes\SUPERAntiSpywareContextMenuExt.SASCon.1
Software\CommView
SOFTWARE\Cygwin
Software\eEye Digital Security
SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\wireshark.exe
Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Start Menu2\Programs\APIS32
Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Start Menu2\Programs\Debugging Tools for Windows (x86)
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\APIS32
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ERUNT_is1
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Oracle VM VirtualBox Guest Additions
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Sandboxie
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Win Sniffer_is1
SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Wireshark
SOFTWARE\SUPERAntiSpyware.com
Software\Syser Soft
Software\Win Sniffer
SOFTWARE\ZxSniffer
SYSTEM\CurrentControlSet\Services\IRIS5
SYSTEM\CurrentControlSet\Services\SbieDrv
SYSTEM\CurrentControlSet\Services\SDbgMsg
SYSTEM\CurrentControlSet\Services\VBoxGuest
If the said processes or registry keys are found, it does not continue to perform its intended routine.
It also redirects to the following URL when the user attemps to search using the specific domains:
- http://{BLOCKED}la.com/?&uid=%d&q={searchTerms}
It also attempts to open the file %System Root%\cgvi5r6i\vgdgfd.72g.
SOLUTION
9.300
9.898.04
05 May 2013
9.899.00
06 May 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_SIMDA.OFP
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\RunOnce
- {random name} = "%Application Data%\{random name}.exe"
- {random name} = "%Application Data%\{random name}.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- ConsentPromptBehaviorAdmin = "0"
- ConsentPromptBehaviorAdmin = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- ConsentPromptBehaviorUser = "0"
- ConsentPromptBehaviorUser = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- EnableLUA = "0"
- EnableLUA = "0"
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows
- update = "shortcut"
- update = "shortcut"
Step 5
Search and delete the file detected as BKDR_SIMDA.OFP
Step 6
Search and delete these files
- %Application Data%\{random name}.reg
- %Application Data%\mcp.ico
- %Desktop%\Computer.lnk
- %User Temp%\{random name}.sys
- %User Temp%\{random number}.tmp
- %User Temp%\{random name}.exe
- %User Temp%\{random number}.exe
- %System Root%\text.exe
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SIMDA.OFP. 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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