BKDR_ZEGOST.DEJ
TrojanDropper:Win32/Zegost.C (Microsoft); BackDoor-CEP.gen.cn (McAfee); Trojan Horse (Symantec); Trojan-PSW.Win32.Bjlog.lfz (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Backdoor.Zegost.J (FSecure)
Windows 2000, Windows XP, Windows Server 2003
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 deletes itself after execution.
TECHNICAL DETAILS
209,582 bytes
EXE
No
04 Apr 2012
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:
- %System Root%\cjxpksqbrp
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It creates the following folders:
- %User Profile%\DRM\%SESSIONNAME%
Other System Modifications
This backdoor deletes the following files:
- %User Profile%\%SESSIONNAME%\xcrke.cc3
- fienlbpfw
- %System Root%\cjxpksqbrp
- uxknwsogwo
- uxbsucvyka
- %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\sOFtwaRe\fienlbpfw
HKEY_LOCAL_MACHINE\sOFtwaRe\fienlbpfwr
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Comhidserv70
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\MediaResources\msvideo
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\fienlbpfw
seRVicemAIN = "NPGetResourceParent"
HKEY_LOCAL_MACHINE\SOFTWARE\fienlbpfw
seRVicedlL = "%User Profile%\%SESSIONNAME%\xcrke.cc3"
HKEY_LOCAL_MACHINE\SOFTWARE\fienlbpfw
module = "%System Root%\cjxpksqbrp"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Comhidserv70
Description = "{random characters}"
Dropping Routine
This backdoor drops the following files:
- %User Temp%\ydxvvndbwn.dat
(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.)
Other Details
This backdoor deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.200
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
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_LOCAL_MACHINE\sOFtwaRe
- fienlbpfw
- In HKEY_LOCAL_MACHINE\sOFtwaRe
- fienlbpfwr
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
- Comhidserv70
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MediaResources
- msvideo
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_LOCAL_MACHINE\SOFTWARE\fienlbpfw
- seRVicemAIN = "NPGetResourceParent"
- In HKEY_LOCAL_MACHINE\SOFTWARE\fienlbpfw
- seRVicedlL = "%User Profile%\%SESSIONNAME%\xcrke.cc3"
- In HKEY_LOCAL_MACHINE\SOFTWARE\fienlbpfw
- module = "%System Root%\cjxpksqbrp"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Comhidserv70
- Description = "{random characters}"
Step 4
Search and delete this file
- %User Temp%\ydxvvndbwn.dat
Step 5
Search and delete this folder
- %User Profile%\DRM\%SESSIONNAME%
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_ZEGOST.DEJ. 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 7
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.
- %User Profile%\%SESSIONNAME%\xcrke.cc3
- fienlbpfw
- %System Root%\cjxpksqbrp
- uxknwsogwo
- uxbsucvyka
- %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log
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