Worm.Win32.Dorkbot.A_1110a8b127

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 Worm'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 Worm creates the following process(es):

Lskmkx.exe:676
%original file name%.exe:572

The Worm injects its code into the following process(es):No processes have been created.

File activity

The process %original file name%.exe:572 makes changes in the file system.

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

%Documents and Settings%\%current user%\Application Data\Lskmkx.exe (1425 bytes)

Registry activity

The process Lskmkx.exe:676 makes changes in the system registry.

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

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "40 A5 3C 0A D2 B2 A3 FA 36 FE BC 8F 25 C3 B2 68"

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

The process %original file name%.exe:572 makes changes in the system registry.

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

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "DD 48 DE 09 81 90 D9 70 76 79 98 83 81 50 56 98"

[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 Worm 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.

HOSTS file anomalies

No changes have been detected.

Rootkit activity

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

HttpSendRequestW
InternetWriteFile
HttpSendRequestA

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

send

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

MoveFileA
CopyFileW
CopyFileA
MoveFileW
CreateFileW
CreateFileA

The Worm 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 Worm'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:676
   %original file name%.exe:572
   

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

   %Documents and Settings%\%current user%\Application Data\Lskmkx.exe (1425 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