Backdoor.Win32.SIMDA.C003X3KR19


 ALIASES:

Backdoor:Win32/Simda.gen!B [generic] (Microsoft); BackDoor-FDOB!59B6B0F13C4C (McAfee); Mal/Emogen-Y (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size:

589,824 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Jan 2020

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.

Autostart Technique

This Backdoor modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
userinit = "%System%\userinit.exe,%Windows%\apppatch\svchost.exe,"

(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)

Other System Modifications

This Backdoor deletes the following files:

  • %Program Files%\AVG\AVG9\dfncfg.dat
  • {malware file path and name}
  • %Windows%\AppPatch\svchost.exe_

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
1cca0df5 = "{random characters}"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
1CCA0967a

Dropping Routine

This Backdoor drops the following files:

  • %Windows%\AppPatch\svchost.exe
  • %All Users Profile%\PrevxCSI\csidb.csi
  • %Program Files%\AVG\AVG9\dfmcfg.dat

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}t.com/login.php
  • http://{BLOCKED}h.com/login.php
  • http://{BLOCKED}w.com/login.php
  • http://{BLOCKED}j.com/login.php
  • http://{BLOCKED}r.com/login.php
  • http://www.{BLOCKED}h.com/login.php
  • http://{BLOCKED}s.com/login.php
  • http://{BLOCKED}l.com/login.php
  • http://{BLOCKED}f.com/login.php
  • http://{BLOCKED}c.com/login.php
  • http://{BLOCKED}w.com/hbt.php?rewrite=login.php
  • http://www.{BLOCKED}t.com/login.php
  • http://usd.{BLOCKED}bra.com/zcvisitor/{GUID}?campaignid={GUID}
  • http://www.{BLOCKED}s.com
  • http://www.{BLOCKED}w.com/hbt.php?rewrite=login.php
  • http://{BLOCKED}d.com/login.php
  • http://{BLOCKED}d.com/index.html
  • http://{BLOCKED}m.com/login.php
  • http://{BLOCKED}n.com/login.php
  • http://{BLOCKED}b.com/login.php
  • http://www.{BLOCKED}n.com
  • http://www.{BLOCKED}n.com/default.php
  • http://{BLOCKED}z.com/login.php
  • http://www.{BLOCKED}s.com/login.php
  • http://{BLOCKED}g.com/login.php
  • http://ww55.{BLOCKED}b.com
  • http://{BLOCKED}v.com/login.php
  • http://{BLOCKED}x.com/login.php
  • http://www.{BLOCKED}x.com/login.php
  • http://usa.{BLOCKED}bra.com/zcvisitor/{GUID}?campaignid={GUID}
  • http://ww11.{BLOCKED}b.com
  • http://www.{BLOCKED}g.com
  • http://{BLOCKED}p.com
  • http://{BLOCKED}q.com
  • http://{BLOCKED}k.com

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and delete files detected as Backdoor.Win32.SIMDA.C003X3KR19 using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • 1cca0df5 = "{random characters}"

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: userinit = "%System%\userinit.exe,%Windows%\apppatch\svchost.exe,"
      To: userinit = ""%Windows%\system32\userinit.exe,""

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %Windows%\AppPatch\svchost.exe
  • %All Users Profile%\PrevxCSI\csidb.csi
  • %Program Files%\AVG\AVG9\dfmcfg.dat

Step 6

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.SIMDA.C003X3KR19. 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 the following Trend Micro Support pages for more information:

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Program Files%\AVG\AVG9\dfncfg.dat
  • {malware file path and name}
  • %Windows%\AppPatch\svchost.exe_

Step 8

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • 1CCA0967a


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