BKDR_BANKDOK

BANDOK is a family consisting of remote access tools (RATs) that enables remote attackers from accessing the infected system. In order to take full control of the system, it uses a server creator, a client, and a server. It also makes use of process hijacking / kernel patching to bypass the firewall. When executed, BANDOK variants access URLs to download other components.

Installation

This Trojan drops the following files:

• %System Root%\Documents and Settings\All Users\Application Data\loggy.txt
• %System%\csrss{number}.dll
• %User Temp%\csrss{number}.dll

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %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 drops the following copies of itself into the affected system:

• %System Root%\Documents and Settings\All Users\Application Data\csrss.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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
Svchost = "%System Root%\Documents and Settings\All Users\Application Data\csrss.exe"

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
SvchostID = "{machine ID converted}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
SvchostVersion = "{number}"

HKEY_USERS\.DEFAULT\SOFTWARE\
Microsoft\Windows\CurrentVersion
SvchostVersion = "{number}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters
110:TCP = "110:TCP:*:Enabled:svchost"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System Root%\Documents and Settings\All Users\Application Data\csrss.exe = "%System Root%\Documents and Settings\All Users\Application Data\csrss:*:Enabled:svchost"

It adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Servers

Other Details

This Trojan connects to the following possibly malicious URL:

• http://{BLOCKED}lero.com/s.html?cachingDeny={random characters}&id={converted machine ID}
• http://{BLOCKED}stats.ru/s.html?cachingDeny={random characters}&id={converted machine ID}
• http://{BLOCKED}tats.ru/s.html?cachingDeny={random characters}&id={converted machine ID}
• http://{BLOCKED}ler.com/s.html?cachingDeny={random characters}&id={converted machine ID}
• http://{BLOCKED}-ana1itics.com/s.html?cachingDeny={random characters}&id={converted machine ID}
• http://{BLOCKED}machiner.com/s.html?cachingDeny={random characters}&id={converted machine ID}