Backdoor.Win32.PcClient_37d43ec542

by malwarelabrobot on January 22nd, 2014 in Malware Descriptions.

Gen:Variant.Barys.21566 (BitDefender), HEUR:Trojan.Win32.Generic (Kaspersky), Trojan.Inject1.25873 (DrWeb), Gen:Variant.Barys.21566 (B) (Emsisoft), Artemis!37D43EC54293 (McAfee), Trojan.Inject (Ikarus), Gen:Variant.Barys.21566 (FSecure), Inject.AKZA (AVG), MSIL:Injector-FT [Trj] (Avast), Backdoor.Win32.PcClient.FD, Trojan.Win32.IEDummy.FD, WormRebhip.YR, GenericAutorunWorm.YR, GenericInjector.YR (Lavasoft MAS)
Behaviour: Trojan, Backdoor, Worm, WormAutorun


The description has been automatically generated by Lavasoft Malware Analysis System and it may contain incomplete or inaccurate information.

Summary
Technical Details
Removal Recommendations

MD5: 37d43ec54293125bc3531348d1211531
SHA1: e107bd6f17bf7b2c9189d7b8aaf51ce0857143c5
SHA256: 8202ac25fddac3dfb10b40ac11dc43213509cd76341d73a5f0a576bf6b8a33f4
SSDeep: 6144:DNnzIR5/0jYoMgNhr8lrLQu0tG/7Ex2gZKz8HpiKv13ceSPi:Oz8X5arsLGQxC8kK eSK
Size: 303616 bytes
File type: EXE
Platform: WIN32
Entropy: Packed
PEID: MicrosoftVisualC, NETexecutable, UPolyXv05_v6
Company: no certificate found
Created at: 2014-01-19 15:31:14
Analyzed on: WindowsXP SP3 32-bit


Summary:

Backdoor. Malware that enables a remote control of victim's machine.

Payload

Behaviour Description
WormAutorun A worm can spread via removable drives. It writes its executable and creates "autorun.inf" scripts on all removable drives. The autorun script will execute the Backdoor's file once a user opens a drive's folder in Windows Explorer.


Process activity

The Backdoor creates the following process(es):

server.exe:1760
vbc.exe:524

The Backdoor injects its code into the following process(es):

%original file name%.exe:1124
rundll32.exe:1040
iexplore.exe:1860

File activity

The process iexplore.exe:1860 makes changes in the file system.
The Backdoor creates and/or writes to the following file(s):

%Documents and Settings%\%current user%\Local Settings\Temp\XxX.xXx (16656 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\UuU.uUu (40 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\photo.jpg (12 bytes)
%Documents and Settings%\%current user%\Application Data\logs.dat (15 bytes)

The Backdoor deletes the following file(s):

%Documents and Settings%\%current user%\Local Settings\Temp\UuU.uUu (0 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\XxX.xXx (0 bytes)
%WinDir%\Microsoft.NET\Framework\v2.0.50727\vbc.exe (0 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\XX--XX--XX.txt (0 bytes)

The process vbc.exe:524 makes changes in the file system.
The Backdoor creates and/or writes to the following file(s):

C:\dir\install\install\server.exe (7547 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\XX--XX--XX.txt (247 bytes)

Registry activity

The process server.exe:1760 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "B1 ED 43 32 8C B2 77 1F FA 3C AB 23 1E 87 1D 76"

The process %original file name%.exe:1124 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "CD 85 73 85 F4 DB 41 35 14 D2 5D 8A 13 DB 62 53"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"AppData" = "%Documents and Settings%\%current user%\Application Data"

"Cache" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files"

To automatically run itself each time Windows is booted, the Backdoor adds the following link to its file to the system registry autorun key:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
"CryptedFile" = "c:\%original file name%.exe"

The process rundll32.exe:1040 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "4A 32 D9 1C BE 60 D0 C2 D0 15 BC 8F 85 39 AD 2F"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd73-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{5c14c4f6-74da-11e2-81b0-000c29ec7fc5}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd72-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd75-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

The process iexplore.exe:1860 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "C1 71 75 EC 91 C5 52 D1 70 39 17 FE 88 E0 1E 0B"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd73-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{5c14c4f6-74da-11e2-81b0-000c29ec7fc5}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Cookies" = "%Documents and Settings%\%current user%\Cookies"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Common Documents" = "%Documents and Settings%\All Users\Documents"

[HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache\%System%]
"shimgvw.dll" = "Windows Picture and Fax Viewer"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Desktop" = "%Documents and Settings%\%current user%\Desktop"
"Personal" = "%Documents and Settings%\%current user%\My Documents"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd72-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd75-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Common Desktop" = "%Documents and Settings%\All Users\Desktop"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Cache" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files"

[HKCU\Software\vítima]
"NewIdentification" = "vítima"
"FirstExecution" = "21/01/2014 -- 02:24"

[HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache\c:\dir\install\install]
"server.exe" = "Visual Basic Command Line Compiler"

The Backdoor modifies IE settings for security zones to map all urls to the Intranet Zone:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap]
"IntranetName" = "1"

The Backdoor modifies IE settings for security zones to map all local web-nodes with no dots which do not refer to any zone to the Intranet Zone:

"UNCAsIntranet" = "1"

The Backdoor modifies IE settings for security zones to map all web-nodes that bypassing proxy to the Intranet Zone:

"ProxyBypass" = "1"

The process vbc.exe:524 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "E6 51 E1 91 A0 8A 1A 84 1C 3D 46 65 19 91 76 CB"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run]
"Policies" = "c:\dir\install\install\server.exe"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run]
"Policies" = "c:\dir\install\install\server.exe"

[HKLM\SOFTWARE\Microsoft\Active Setup\Installed Components\{22QQL07Y-NV6Q-3VY4-1760-8U8184K7KVX4}]
"StubPath" = "c:\dir\install\install\server.exe Restart"

Network activity (URLs)

No activity has been detected.

HOSTS file anomalies

No changes have been detected.

Rootkit activity

No anomalies have been detected.

Propagation

A worm can spread via removable drives. It writes its executable and creates "autorun.inf" scripts on all removable drives. The autorun script will execute the Backdoor's file once a user opens a drive's folder in Windows Explorer.


Remove it with Ad-Aware

  1. Click (here) to download and install Ad-Aware Free Antivirus.
  2. Update the definition files.
  3. Run a full scan of your computer.


Manual removal*

  1. Terminate malicious process(es) (How to End a Process With the Task Manager):

    server.exe:1760
    vbc.exe:524

  2. Delete the original Backdoor file.
  3. Delete or disinfect the following files created/modified by the Backdoor:

    %Documents and Settings%\%current user%\Local Settings\Temp\XxX.xXx (16656 bytes)
    %Documents and Settings%\%current user%\Local Settings\Temp\UuU.uUu (40 bytes)
    %Documents and Settings%\%current user%\Local Settings\Temp\photo.jpg (12 bytes)
    %Documents and Settings%\%current user%\Application Data\logs.dat (15 bytes)
    C:\dir\install\install\server.exe (7547 bytes)
    %Documents and Settings%\%current user%\Local Settings\Temp\XX--XX--XX.txt (247 bytes)

  4. Delete the following value(s) in the autorun key (How to Work with System Registry):

    [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
    "CryptedFile" = "c:\%original file name%.exe"

  5. Find and delete all copies of the worm's file together with "autorun.inf" scripts on removable drives.
  6. Reboot the computer.

*Manual removal may cause unexpected system behaviour and should be performed at your own risk.