BKDR_IRCBOT.FAG

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It listens on ports. It may also connect to Internet Relay Chat (IRC) servers and receive commands from a remote user.

It performs denial of service (DoS) attacks on affected systems using specific flooding method(s).

As of this writing, the said sites are inaccessible.

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following files:

• %User Profile%\Application Data\new.bin

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It drops the following copies of itself into the affected system:

• %User Profile%\Application Data\RECYCLER\logon.exe
• %User Profile%\Application Data\winlogon.scr

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It injects itself into the following processes running in the affected system's memory:

• explorer.exe

It creates the following folders:

• %User Profile%\Application Data\RECYCLER

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• bvjfdusnc

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
Remote Shell Manager = "%User Profile%\Application Data\RECYCLER\logon.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Windows Protect Manager = "%User Profile%\Application Data\winlogon.scr"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = ".exe;.scr;"

Backdoor Routine

This Trojan listens on the following ports:

• 7081

It connects to any of the following IRC server(s):

• d.{BLOCKED}book.com

It may also connect to Internet Relay Chat (IRC) servers and receive commands from a remote user.

Denial of Service (DoS) Attack

This Trojan performs denial of service (DoS) attacks on affected systems using the following flooding method(s):

• SYN flood
• UDP flood

Download Routine

This Trojan accesses the following websites to download files:

• http://{BLOCKED}.{BLOCKED}.246.148/july/1888.exe

As of this writing, the said sites are inaccessible.

NOTES:

The remote command received may contain its propagation routine through IRC.