TROJ_TRACUR.SMA

This Trojan may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following copies of itself into the affected system:

• %Windows%\{random characters}wow.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

It drops the following non-malicious file:

• %System%\A887E64515035F9F82BAF1D4BC896D65\unrar.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

• %System%\A887E64515035F9F82BAF1D4BC896D65
• %System%\A887E64515035F9F82BAF1D4BC896D65\b
• %System%\A887E64515035F9F82BAF1D4BC896D65\h

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random characters}wow.exe = "%Windows%\{random characters}wow.exe"

Other System Modifications

This Trojan creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\{random characters}wow.exe = "%Windows%\{random characters}wow.exe:*:Enabled:Windows Update Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\{random characters}wow.exe = "%Windows%\{random characters}wow.exe:*:Enabled:Windows Update Service"

Download Routine

This Trojan downloads an updated copy of itself from the following website(s):

• http://{BLOCKED}230.12/bin_v85.rar

It connects to the following URL(s) to download its configuration file:

• http://{BLOCKED}.1.174/update/{random characters}
• http://{BLOCKED}.53.210/update/{random characters}
• http://{BLOCKED}.153.48/update/{random characters}

It saves the files it downloads using the following names:

• %System%\A887E64515035F9F82BAF1D4BC896D65\{random number}.tmp

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

NOTES:

The downloaded configuration file contains the URLs containing the update. The URLs are saved in the file %System%\A887E64515035F9F82BAF1D4BC896D65\ntuser.dat. However, the configuration file is not saved in the computer.

The downloaded update is a compressed .RAR archive. It uses the dropped file %System%\A887E64515035F9F82BAF1D4BC896D65\unrar.exe to extract the compressed updated copy of the malware. It then executes the update with the command-line parameters -upd -fd%Windows%\{random characters}wow.exe. The command-line parameter -fd causes the newer version of the malware to delete the older version of the malware. Trend Micro detects the downloaded update as TROJ_TRACUR.SMB.