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TROJ_CUTWAIL

August 20, 2013
 ALIASES:

Pandex, Harebot, Pushdo

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Spammed via email

In 2009, Trend Micro researchers studied the relationship between the Pushdo botnet and CUTWAIL malware. It appeared that CUTWAIL is one of the malware downloaded by Pushdo and is used by the botnet mainly for spamming. Later on, the Pushdo botnet was also referred to as the Cutwail botnet.

In the botnet business model, CUTWAIL is one of the main starters of infections of ZEUS, and later on, FAKEAV. When a system is infected by CUTWAIL malware, it usually downloads a ZEUS or FAKEAV malware on the affected system as well.

Apart from its downloading routine, CUTWAIL is also known to perform distributed denial of service (DDoS) attacks against various sites. Sites that have been attacked by CUTWAIL are affiliated with various government agencies in differing countries. It also attacked several commercial sites.

  TECHNICAL DETAILS

Memory Resident:

Yes

Payload:

Connects to URLs/IPs, Downloads files, Launches DoS/DDoS attacks

Installation

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

  • %System%\imPlayok.exe
  • %System%\pmpviotnY.exe
  • %System%\reader_s.exe
  • %System%\reader_s.exe
  • %System%\wuaucldt.exe
  • %User Profile%\imPlayok.exe
  • %User Profile%\pmpviotnY.exe
  • %User Profile%\reader_s.exe
  • %User Profile%\wuaucldt.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
syncman = "%User Profile%\wuaucldt.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
syncman = "%System%\wuaucldt.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
reader_s = "%User Profile%\reader_s.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
reader_s = "%System%\reader_s.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
pmpviotnY = "%User Profile%\pmpviotnY.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
pmpviotnY = "%System%\pmpviotnY.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
imPlayok = "%User Profile%\imPlayok.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
imPlayok = "%System%\imPlayok.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.76.194
  • {BLOCKED}.{BLOCKED}.62.66
  • {BLOCKED}.{BLOCKED}.220.203
  • {BLOCKED}.{BLOCKED}.187.4
  • black.{BLOCKED}antom.com
  • {BLOCKED}ash.com