BKDR_BISTDOR.SMI

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.

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:

• %User Temp%\~imsinst.exe

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

It creates the following folders:

• %Program Files%\FilePop
• %Program Files%\FilePop\html

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Other System Modifications

This backdoor deletes the following files:

• %User Temp%\~imsinst.tmp
• %User Temp%\M039D~1.EXE

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Enable = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Size = "a"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
InitHits = "64"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Factor = "14"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\www.skdos.com
Description = "www.skdos.com"

Dropping Routine

This backdoor drops the following files:

• ÇìÂm.exe
• jre6u26windowsi586_fsetup_776_18.exe
• %User Temp%\~imsinst.tmp
• %System%\skdos.exe

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

Other Details

This backdoor connects to the following possibly malicious URL:

• http://filepop.{BLOCKED}o.kr/App/auto/ControlNotifier/newagree.dat
• http://filepop.{BLOCKED}o.kr/App/etcApp/agreement_filepop.html
• http://down.{BLOCKED}zi.co.kr/agree/agreement_{BLOCKED}zi.txt
• http://down.{BLOCKED}o.com/main/agreement/agreement_{BLOCKED}o.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_yahoo.html
• http://{BLOCKED}ool-pc.{BLOCKED}o.kr/etc/yak_app.htm
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_windowviewcon.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_linelink.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_wizeni.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_winpro.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_sidematch.html
• http://up1.{BLOCKED}e.co.kr/etcApp/agreement/agreement_IEtab.html
• http://filepop.{BLOCKED}o.kr/App/z_file/?dCode=776

This report is generated via an automated analysis system.