Trojan.Win32.VBKrypt.dbvr_aa69713939

Dynamic Analysis

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 Trojan's file once a user opens a drive's folder in Windows Explorer.
IRCBot	A bot can communicate with command and control servers via IRC channel.
UDPFlooder	This program can make a UDP flood. A UDP flood attack is a denial-of-service attack using the User Datagram Protocol (UDP). It can be initiated by sending a large number of UDP packets to random ports on a remote host.
USBInfector	A program can register a device notification with the help of RegisterDeviceNotification. So it is notified when a USB device is plugged and then the worm copies itself to the USB device plugged into the affected computer.

Process activity

The Trojan creates the following process(es):

Lskmkx.exe:1352
Lskmkx.exe:1160
aa69713939f34e770153ff4e5951ed88.exe:876
aa69713939f34e770153ff4e5951ed88.exe:1836

File activity

The process aa69713939f34e770153ff4e5951ed88.exe:1836 makes changes in a file system.

The Trojan creates and/or writes to the following file(s):

%Documents and Settings%\%current user%\Application Data\Lskmkx.exe (10177 bytes)

Registry activity

The process Lskmkx.exe:1352 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "66 60 58 19 4F 8B 4C F5 7C B1 FA DE 43 74 26 C5"

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

The process Lskmkx.exe:1160 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "B2 9C A0 92 BD 7C 76 FE 44 D5 97 91 E4 24 DB 8B"

The process aa69713939f34e770153ff4e5951ed88.exe:876 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "92 73 97 F6 32 5E A1 FF 89 57 A3 8B B6 A5 0F 80"

The process aa69713939f34e770153ff4e5951ed88.exe:1836 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "9A CA FB 81 AC F7 14 97 7C 13 76 4E AF 93 C2 11"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system]
"Shell" = "explorer.exe,%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

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

[HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
"Shell" = "explorer.exe,%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

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

[HKU\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run]
"Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
"Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

Network activity (URLs)

No activity has been detected.

Rootkit activity

The Trojan installs the following user-mode hooks in WININET.dll:

HttpSendRequestW
InternetWriteFile
HttpSendRequestA

The Trojan installs the following user-mode hooks in WS2_32.dll:

send

The Trojan installs the following user-mode hooks in kernel32.dll:

MoveFileA
CopyFileW
CopyFileA
MoveFileW
CreateFileW
CreateFileA

The Trojan installs the following user-mode hooks in ntdll.dll:

LdrLoadDll
NtResumeThread
NtQueryDirectoryFile
NtEnumerateValueKey

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 Trojan's file once a user opens a drive's folder in Windows Explorer.A program can register a device notification with the help of RegisterDeviceNotification. So it is notified when a USB device is plugged and then the worm copies itself to the USB device plugged into the affected computer.

Removals

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. Scan a system with an anti-rootkit tool.
   
2. Terminate malicious process(es) (How to End a Process With the Task Manager):

   Lskmkx.exe:1352
   Lskmkx.exe:1160
   aa69713939f34e770153ff4e5951ed88.exe:876
   aa69713939f34e770153ff4e5951ed88.exe:1836
   

3. Delete the original Trojan file.
   
4. Delete or disinfect the following files created/modified by the Trojan:

   %Documents and Settings%\%current user%\Application Data\Lskmkx.exe (10177 bytes)

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

   [HKU\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run]
   "Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"
   
   [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   "Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"
   
   [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   "Lskmkx" = "%Documents and Settings%\%current user%\Application Data\Lskmkx.exe"

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

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

Static Analysis

Network Activity

Map

Strings from Dumps