Backdoor.Win32.RUSKILL.AB
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 adds the following processes:
- {malware file path and name}
- %Program Files%\Internet Explorer\iexplore.exe
- "%System Root%\Program Files\Internet Explorer\IEXPLORE.EXE"
- "%Program Files%\Internet Explorer\IEXPLORE.EXE" SCODEF:2316 CREDAT:275457 /prefetch:2
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
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
Mqucuo = "%Application Data%\Mqucuo.scr"
Other System Modifications
This Backdoor modifies the following file(s):
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\82DF2NUK\www.msn[1].xml
It deletes the following files:
- %AppDataLocal%Low\Microsoft\Internet Explorer\Services\search_{0633EE93-D776-472f-A0FF-E1416B8B2E3A}.ico
(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
Dropping Routine
This Backdoor drops the following files:
- %AppDataLocal%\Microsoft\Internet Explorer\DomainSuggestions\en-US.6
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\{974DF917-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\RecoveryStore.{8F8F1ED3-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\MSIMGSIZ.DAT
- %AppDataLocal%\Microsoft\Internet Explorer\imagestore\joppu72\imagestore.dat
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\{8F8F1ED5-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\82DF2NUK\www.msn[1].xml
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\3UYAQU1F\tag.idsync.analytics.yahoo[1].xml
- %Application Data%\Mqucuo.scr
This report is generated via an automated analysis system.
SOLUTION
Step 1
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.
Step 2
Restart in Safe Mode
Step 3
Identify and terminate files detected as Backdoor.Win32.RUSKILL.AB
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Mqucuo = "%Application Data%\Mqucuo.scr"
Step 5
Search and delete these components
- %AppDataLocal%\Microsoft\Internet Explorer\DomainSuggestions\en-US.6
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\{974DF917-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\RecoveryStore.{8F8F1ED3-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\MSIMGSIZ.DAT
- %AppDataLocal%\Microsoft\Internet Explorer\imagestore\joppu72\imagestore.dat
- %AppDataLocal%\Microsoft\Internet Explorer\Recovery\High\Active\{8F8F1ED5-1807-11EA-86AF-005056BC3261}.dat
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\82DF2NUK\www.msn[1].xml
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\3UYAQU1F\tag.idsync.analytics.yahoo[1].xml
- %Application Data%\Mqucuo.scr
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.RUSKILL.AB. 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 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.
- %AppDataLocal%\Microsoft\Internet Explorer\DOMStore\82DF2NUK\www.msn[1].xml
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.
- %AppDataLocal%Low\Microsoft\Internet Explorer\Services\search_{0633EE93-D776-472f-A0FF-E1416B8B2E3A}.ico
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