TROJ_MICROJOI.GG
TrojanDropper:Win32/Microjoin.gen!C (Microsoft); RDN/Generic Dropper!uz (McAfee); Trojan.Zbot (Symantec); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Dropper.Small.27.AC (AVG)
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: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan 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
88,064 bytes
EXE
Yes
18 Aug 2014
Arrival Details
This Trojan 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 Trojan creates the following folders:
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\Wilbert
- %User Profile%\LOCALS~1
- %User Temp%\Hs_
- %User Temp%\88421
- %User Temp%\88421\....
(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.. %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.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
AutoRun = "%User Temp%\stl.exe"
Other System Modifications
This Trojan deletes the following files:
- %User Temp%\ope1.tmp
- %User Temp%\ope4.tmp
(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It deletes the following folders:
- %User Temp%\88421\TemporaryFile
(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
DnsCacheEnabled = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
DnsCacheTimeout = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ServerInfoTimeOut = "0"
Dropping Routine
This Trojan drops the following files:
- %User Temp%\adl.exe
- %User Temp%\stl.exe
- %User Temp%\58b8052567ade6540adf05ec8d813970.zip
- %System Root%\koreaautoup.bmp
- %System%\drivers\etc\hosts.ics
(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %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.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}75.72
- http://user.{BLOCKED}e.qq.com/1874081740
- {BLOCKED}0.1
- {BLOCKED}.8.99
It deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.700
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
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\Microsoft\Windows Script
- Settings
Step 4
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\Microsoft\Windows\CurrentVersion\Run
- AutoRun = "%User Temp%\stl.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows Script\Settings
- JITDebug = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- DnsCacheEnabled = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- DnsCacheTimeout = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- ServerInfoTimeOut = "0"
Step 5
Search and delete these components
- %User Temp%\adl.exe
- %User Temp%\stl.exe
- %User Temp%\58b8052567ade6540adf05ec8d813970.zip
- %System Root%\koreaautoup.bmp
- %System%\drivers\etc\hosts.ics
Step 6
Search and delete these folders
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\Wilbert
- %User Profile%\LOCALS~1
- %User Temp%\Hs_
- %User Temp%\88421
- %User Temp%\88421\....
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_MICROJOI.GG. 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 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 Temp%\ope1.tmp
- %User Temp%\ope4.tmp
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