BKDR_DARKOMET.ENJ
Backdoor:Win32/Fynloski.R (Microsoft); RDN/Spybot.bfr!r (McAfee); Trojan.Gen.2 (Symantec); Trojan-PSW.Win32.Tepfer.pswsqw (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse MSIL8.AJKL (AVG)
Windows
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.
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%\Windows\bthserv.exe
(Note: %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.)
It creates the following folders:
- %User Profile%\Application Data\dclogs
(Note: %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.)
Other System Modifications
This backdoor modifies the following file(s):
- %Application Data%\GDIPFONTCACHEV1.DAT
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It deletes the following files:
- {malware path and file name}:zone.identifier
- Desktop:Zone.Identifier
- %User Profile%\Windows\AdobeARMservice.exe:Zone.Identifier
- %Desktop%\PP.exe:Zone.Identifier
- %User Profile%\Windows\bthserv.exe:Zone.Identifier
(Note: %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.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
HKEY_CURRENT_USER\Software\WinRAR
It adds the following registry entries:
HKEY_CURRENT_USER\Software\WinRAR
HWID = "{random values}"
HKEY_CURRENT_USER\Software\DC3_FEXEC
6/29/2015 at 10:03:44 PM = "{1c6961c0-f82d-11e0-a6bd-806d6172696f-1756172240}"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
GDIPlus
FontCachePath = "%Application Data%"
(Note: The default value data of the said registry entry is %User Profile%\Local Settings\Application Data.)
Dropping Routine
This backdoor drops the following files:
- %Desktop%\PP.exe
- %User Profile%\Windows\AdobeARMservice.exe
(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %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.)
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}.78.163
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
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
- In HKEY_CURRENT_USER\Software
- WinRAR
Step 3
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\WinRAR
- HWID = "{random values}"
- In HKEY_CURRENT_USER\Software\DC3_FEXEC
- 6/29/2015 at 10:03:44 PM = "{1c6961c0-f82d-11e0-a6bd-806d6172696f-1756172240}"
Step 4
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\GDIPlus
- From: FontCachePath = "%Application Data%"
To: FontCachePath = ""%User Profile%\Local Settings\Application Data""
- From: FontCachePath = "%Application Data%"
Step 5
Search and delete these components
- %Desktop%\PP.exe
- %User Profile%\Windows\AdobeARMservice.exe
Step 6
Search and delete this folder
- %User Profile%\Application Data\dclogs
Step 7
Scan your computer with your Trend Micro product to delete files detected as BKDR_DARKOMET.ENJ. 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.
Step 8
Restore deleted/modified files and/or registry entries from backup
*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- %Application Data%\GDIPFONTCACHEV1.DAT
Step 9
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- {malware path and file name}:zone.identifier
- Desktop:Zone.Identifier
- %User Profile%\Windows\AdobeARMservice.exe:Zone.Identifier
- %Desktop%\PP.exe:Zone.Identifier
- %User Profile%\Windows\bthserv.exe:Zone.Identifier
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