Backdoor.Win32.PcClient_831aace172

by malwarelabrobot on January 24th, 2014 in Malware Descriptions.

HEUR:Trojan.Win32.Generic (Kaspersky), Trojan.Inject!IK (Emsisoft), 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: 831aace172e9d0c427234f7fdc1ae395
SHA1: 7e451f795f7b62eb437f953adc3dc49382f7f0ea
SHA256: ca7ff1f807910218f3e12d05f798d2a3ed857ef16aca210932fb7e041c137032
SSDeep: 6144:6ts nHoAlKVZf5CSFMArscMCHp8vM2b4KSO 8FQzovYKH/NrhBVAK:KdG8SCTEp8Z9QzjKbs
Size: 303616 bytes
File type: EXE
Platform: WIN32
Entropy: Packed
PEID: MicrosoftVisualC, NETexecutable, UPolyXv05_v6
Company: House Of Soft
Created at: 2014-01-20 09:37:01
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:464
vbc.exe:828

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

%original file name%.exe:1724
rundll32.exe:676
iexplore.exe:248

File activity

The process iexplore.exe:248 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 (15528 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:828 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 %original file name%.exe:1724 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "11 0E 11 E3 5C 7A DC FE 71 3F 4A D1 E4 45 E1 8A"

[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 server.exe:464 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "E9 45 DA 78 7B 9E 9F 35 ED AC 73 A8 4E 55 73 3A"

The process rundll32.exe:676 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 8D 9C 84 95 67 92 D8 0C 1D A8 EB 11 AC 77 DF"

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

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

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{b98117e8-75ca-11e2-81b2-000c293708fb}]
"BaseClass" = "Drive"

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

The process iexplore.exe:248 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "D7 79 2D AA EC 26 77 E7 0F F7 88 69 6B D5 A2 14"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd73-744b-11e2-8294-806d6172696f}]
"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\{b98117e8-75ca-11e2-81b2-000c293708fb}]
"BaseClass" = "Drive"

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

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

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

[HKCU\Software\vítima]
"NewIdentification" = "vítima"
"FirstExecution" = "23/01/2014 -- 04:03"

[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:828 makes changes in the system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "D3 CF 02 BD 8B 3D 8F B1 DF 45 F0 FF 6C 7F 34 91"

[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\{4G416E87-WC47-I264-7O22-7BC754RJ6F8F}]
"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:464
    vbc.exe:828

  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 (15528 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.