BKDR_IRCBOT.CJC

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

It deletes the initially executed copy of itself.

Arrival Details

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

• %Windows%\system\wmisvr.exe

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

It drops the following files:

• %System%\drivers\sysdrv32.sys

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WMISRV\
0000
Service = "WMISRV"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WMISRV
ImagePath = "%Windows%\system\wmisvr.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WMISRV
DisplayName = "WMI Servicer"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WMISRV

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WMISRV\
0000

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WMISRV

Other Details

This backdoor connects to the following possibly malicious URL:

• sec.{BLOCKED}icofskorea.info

It deletes the initially executed copy of itself