BKDR_FYNLOSKI.C
Backdoor:Win32/Fynloski.A (Microsoft); PAK:PE_Patch.Enigma (Kaspersky)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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.
However, as of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
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 Profile%\Application Data\bootsys\boot.exe
(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 creates the following folders:
- %User Profile%\Application Data\bootsys
(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.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
syslds = "%User Profile%\Application Data\bootsys\boot.exe"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%User Profile%\Application Data\bootsys\boot.exe"
(Note: The default value data of the said registry entry is %System%\userinit.exe,.)
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
HKEY_CURRENT_USER\Software\Enigma Protector
HKEY_CURRENT_USER\Software\sang sinsang
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = "1"
(Note: The default value data of the said registry entry is 0.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DisableNotifications = "1"
(Note: The default value data of the said registry entry is 0.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = "4"
(Note: The default value data of the said registry entry is 2.)
It also creates the following registry entry(ies) as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "1"
Other Details
This backdoor connects to the following possibly malicious URL:
- http://cafe.{BLOCKED}r.com/csobluedragon03
- {BLOCKED}86.codns.com
However, as of this writing, the said sites are inaccessible.