BKDR_FYNLOSKI.GGTX
Backdoor:Win32/Fynloski.A (Microsoft); Mal/MalitRar-B (Sophos)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Backdoor
Destructiveness: No
Encrypted:
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.
It disables Task Manager, Registry Editor, and Folder Options.
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 creates the following folders:
- %System Root%\Documents and Settings\Wilbert
- %User Profile%\bs9hp336c7y24
- %User Profile%\Application Data\dclogs
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
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\RunOnce
bs9hp336c7y24 = "%User Profile%\bs9hp336c7y24\icdjfqevrziqmv.vbs"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = "1"
Dropping Routine
This backdoor drops the following files:
- __tmp_rar_sfx_access_check_37546
- mWszEpgSNk.WKT
- JHYQCOwvMt.exe
- rjGGKqGFBfN.EIC
- mxMQVzEB.GXA
- %User Startup%\start.lnk
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}0.1
This report is generated via an automated analysis system.
SOLUTION
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Restart in Safe Mode
Step 3
Enable Registry Editor, Task Manager, and Folder options
Step 4
Delete this registry key
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software
- DC3_FEXEC
Step 5
Delete this registry value
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- bs9hp336c7y24 = "%User Profile%\bs9hp336c7y24\icdjfqevrziqmv.vbs"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- ShowSuperHidden = "0"
Step 6
Search and delete these components
- __tmp_rar_sfx_access_check_37546
- mWszEpgSNk.WKT
- JHYQCOwvMt.exe
- rjGGKqGFBfN.EIC
- mxMQVzEB.GXA
- %User Startup%\start.lnk
Step 7
Search and delete these folders
- %System Root%\Documents and Settings\Wilbert
- %User Profile%\bs9hp336c7y24
- %User Profile%\Application Data\dclogs
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_FYNLOSKI.GGTX. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.
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