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BKDR_SIMDA.SMEP2

April 12, 2015
 Analysis by: Homer Pacag
 ALIASES:

Backdoor:Win32/Simda (Microsoft); Backdoor.Win32.Simda.adrh (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email, Downloaded from the Internet, Dropped by other malware


This malware, which is known for its HOSTS file modification routines, is related to the SIMDA botnet. Last April 2015, Trend Micro together with Cyber Defense Institute, Interpol, and other security vendors collaborated for the takedown of the said botnet.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

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.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

643,072 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Mar 2015

Payload:

Modifies HOSTS file, Connects to URLs/IPs, Steals information

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:

  • %User Profile%\Application Data\{random}.reg
  • %User Profile%\Application Data\mcp.ico
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}\searchplugins\search.xml
  • %Desktop%\Computer.lnk
  • %User Temp%\{random}.sys
  • %User Temp%\{random}-{random}.exe
  • %User Temp%\{random number}.tmp
  • %User Temp%\{random}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in 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.. %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.)

It drops the following copies of itself into the affected system:

  • %User Profile%\Application Data\ScanDisc.exe
  • %User Profile%\Application Data\{random}.exe
  • %User Temp%\{Random Number}.tmp

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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.)

It executes then deletes itself afterward.

Autostart Technique

This backdoor creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
{random name} = "%User Profile%\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"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{GUID}
NameServer = "8.8.8.8"

(Note: The default value data of the said registry entry is "".)

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}9.{BLOCKED}6.87.106
  • report.{pseudorandom}.com
  • update.{pseudorandom}.com
  • {BLOCKED}9.{BLOCKED}3.196.94
  • {BLOCKED}9.{BLOCKED}7.173.222
  • {BLOCKED}9.{BLOCKED}6.66.239
  • {BLOCKED}.{BLOCKED}9.248.152

Download Routine

This backdoor connects to the following website(s) to download and execute a malicious file:

  • http://update1.{BLOCKED}exefeed.eu/?abbr=RTK&action=download&setupType=umx&setupFileName=process_64.exe
  • http://update1.{BLOCKED}exefeed.eu/?abbr=RTK&action=download&setupType=um32&setupFileName=process_32.exe

HOSTS File Modification

This backdoor modifies the system's HOSTS files to redirect users once the following Web site(s) are accessed:

  • google-analytics.com
  • bing.com
  • connect.facebook.net

Information Theft

This backdoor gathers the following data:

  • Volume Information
  • Language Information
  • Computer Name
  • Network Adapter
  • SusClientId
  • Product Id
  • Windows Install Date

Other Details

This backdoor checks for the presence of the following process(es):

  • vba32arkit.exe
  • cv.exe
  • irise.exe
  • IrisSvc.exe
  • wireshark.exe
  • dumpcap.exe
  • ZxSniffer.exe
  • Aircrack-ng Gui.exe
  • observer.exe
  • tcpdump.exe
  • WinDump.exe
  • wspass.exe
  • Regshot.exe
  • ollydbg.exe
  • PEBrowseDbg.exe
  • windbg.exe
  • DrvLoader.exe
  • SymRecv.exe
  • Syser.exe
  • apis32.exe
  • VBoxService.exe
  • VBoxTray.exe
  • SbieSvc.exe
  • SbieCtrl.exe
  • SandboxieRpcSs.exe
  • SandboxieDcomLaunch.exe
  • SUPERAntiSpyware.exe
  • ERUNT.exe
  • ERDNT.exe
  • EtherD.exe
  • Sniffer.exe
  • CamtasiaStudio.exe
  • CamRecorder.exe

NOTES:

It tries to open a file %System Root%\cgvi5r6i\vgdgfd.72g, which may contain shell commands.

It redirects the following sites when accessed to a designated malware vector.

  • www.bing.com:92.123.68.97
  • bing.com:92.123.68.97
  • gr.bing.com:92.123.68.97
  • ir.bing.com:92.123.68.97
  • gb.bing.com:92.123.68.97
  • dk.bing.com:92.123.68.97
  • au.bing.com:92.123.68.97
  • ro.bing.com:92.123.68.97
  • ca.bing.com:92.123.68.97
  • pt.bing.com:92.123.68.97
  • it.bing.com:92.123.68.97
  • de.bing.com:92.123.68.97
  • es.bing.com:92.123.68.97
  • tr.bing.com:92.123.68.97
  • hu.bing.com:92.123.68.97
  • br.bing.com:92.123.68.97
  • cz.bing.com:92.123.68.97
  • ie.bing.com:92.123.68.97
  • ch.bing.com:92.123.68.97
  • nl.bing.com:92.123.68.97
  • se.bing.com:92.123.68.97
  • no.bing.com:92.123.68.97
  • at.bing.com:92.123.68.97
  • fi.bing.com:92.123.68.97
  • fr.bing.com:92.123.68.97
  • pl.bing.com:92.123.68.97
  • search.yahoo.com:72.30.186.249
  • www.search.yahoo.com:72.30.186.249
  • gr.uk.search.yahoo.com:87.248.112.8
  • ir.uk.search.yahoo.com:100.6.239.84
  • uk.search.yahoo.com:87.248.112.8
  • dk.search.yahoo.com:87.248.112.8
  • au.search.yahoo.com:87.248.112.8
  • ro.search.yahoo.com:87.248.112.8
  • ca.search.yahoo.com:87.248.112.8
  • pt.search.yahoo.com:87.248.112.8
  • it.search.yahoo.com:87.248.112.8
  • de.search.yahoo.com:87.248.112.8
  • es.search.yahoo.com:87.248.112.8
  • tr.search.yahoo.com:87.248.112.8
  • hu.search.yahoo.com:87.248.112.8
  • br.search.yahoo.com:87.248.112.8
  • cz.search.yahoo.com:87.248.112.8
  • ie.search.yahoo.com:87.248.112.8
  • ch.search.yahoo.com:87.248.112.8
  • nl.search.yahoo.com:87.248.112.8
  • se.search.yahoo.com:87.248.112.8
  • no.search.yahoo.com:87.248.112.8
  • fr.search.yahoo.com:87.248.112.8
  • pl.search.yahoo.com:87.248.112.8
  • mx.search.yahoo.com:87.248.112.8
  • search.yahoo.co.jp:87.248.112.8.
  • gr.search.yahoo.com:87.248.112.8
  • malaysia.search.yahoo.com:87.248.112.8
  • vn.search.yahoo.com:87.248.112.8
  • cl.search.yahoo.com:87.248.112.8
  • id.search.yahoo.com:87.248.112.8
  • in.search.yahoo.com:87.248.112.8
  • co.search.yahoo.com:87.248.112.8
  • ph.search.yahoo.com:87.248.112.8
  • nz.search.yahoo.com:87.248.112.8
  • ve.search.yahoo.com:87.248.112.8
  • ar.search.yahoo.com:87.248.112.8
  • fi.search.yahoo.com:87.248.112.8
  • th.search.yahoo.com:87.248.112.8
  • sg.search.yahoo.com:87.248.112.8
  • ch.search.yahoo.com:87.248.112.8
  • at.search.yahoo.com:87.248.112.8
  • za.search.yahoo.com:87.248.112.8
  • cn.search.yahoo.com:87.248.112.8
  • www.google-analytics.com:64.125.87.101
  • google-analytics.com:64.125.87.101
  • connect.facebook.net:64.125.87.101

It checks for the existence of the following registries.

  • HKCU\Software\CommView
  • HKCU\SYSTEM\CurrentControlSet\Services\IRIS5
  • HKCU\Software\eEye Digital Security
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Wireshark
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\wireshark.exe
  • HKCU\SOFTWARE\ZxSniffer
  • HKCU\SOFTWARE\Cygwin
  • HKCU\SOFTWARE\Cygwin
  • HKCU\SOFTWARE\B Labs\Bopup Observer
  • HKCU\AppEvents\Schemes\Apps\Bopup Observer
  • HKCU\Software\B Labs\Bopup Observer
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Win Sniffer_is1
  • HKCU\Software\Win Sniffer
  • HKCU\SOFTWARE\Classes\PEBrowseDotNETProfiler.DotNETProfiler
  • HKCU\Software\Microsoft\tVersion\Explorer\MenuOrder\Start \Debugging Tools for Windows (x86)
  • HKCU\SYSTEM\CurrentControlSet\Services\SDbgMsg
  • HKCU\Software\Microsoft\Windows\CurrentVersion\der\Start Menu2\Programs\APIS32.
  • HKCU\Software\Syser Soft
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\APIS32
  • HKCU\SOFTWARE\APIS32
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Oracle VM VirtualBoxGuest Additions
  • HKCU\SYSTEM\CurrentControlSet\Services\VBoxGuest
  • HKCU\SOFTWARE\Microsoft\tVersion\Uninstall\Sandboxie
  • HKCU\SYSTEM\CurrentControlSet\Services\SbieDrv
  • HKCU\Software\Classes\Folder\shell\sandbox
  • HKCU\Software\Classes\*\shell\sandbox
  • HKCU\SOFTWARE\SUPERAntiSpyware.com
  • HKCU\SOFTWARE\Classes\SUPERAntiSpywareContextMenuExt.SASCon.1
  • HKCU\SOFTWARE\SUPERAntiSpyware.com
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ERUNT_is1
  • HKCU\SYSTEM\ControlSet001\EnumRoot\LEGACY_TBN178D5\0000
  • HKCU\SYSTEM\CurrentControlSet\services\tbn178d5\DisplayName
  • HKCU\SYSTEM\ControlSet001\services\tbn178d5
  • HKCU\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_TBN178D5\0000

It also checks for loaded libraries:

  • SBIEDLL.DLL
  • SBIEDLLX.DLL
  • DBGHELP.DLL

It also checks if the following information are equal:

  • Computer Name = Sandbox
  • User name = CurrentUser
  • File name = file.exe

When a number of conditions are met, the malware executes an infinite loop.

It appends the legitimate file %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}\prefs.js with user_pref("browser.search.selectedEngine", "http://www.bing.com/search?q={searchTerms}");

  SOLUTION

Minimum Scan Engine:

9.750

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

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

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} = "%User Profile%\Application Data\{random name}.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • ConsentPromptBehaviorAdmin = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • ConsentPromptBehaviorUser = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • EnableLUA = "0"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows
    • update = "shortcut"

Step 5

Restore this modified registry value

[ Learn More ]

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{GUID}
    • From: NameServer = "8.8.8.8"
      To: NameServer = ""

Step 6

Remove these strings added by the malware/grayware/spyware in the HOSTS file

[ Learn More ]
    • ::1 localhost

Step 7

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Profile%\Application Data\{random}.reg
  • %User Profile%\Application Data\mcp.ico
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}\searchplugins\search.xml
  • %Desktop%\Computer.lnk
  • %User Temp%\{random}.sys
  • %User Temp%\{random}-{random}.exe
  • %User Temp%\{random number}.tmp
  • %User Temp%\{random}.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SIMDA.SMEP2. 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.

NOTES:

Note: Before proceeding to Step 8, do the following to remove the strings added by the malware/grayware/spyware in the file %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}\prefs.js file.

To edit this file:

  1. Open the file %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}\prefs.js using a text editor such as Notepad.
  2. Find and delete the following entry:
    • user_pref("browser.search.selectedEngine", "http://www.bing.com/search?q={searchTerms}");
  3. Save the file then close the text editor.


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