Upon execution, this worm sends an HTTP request to its C&C to download a file.
It saves the downloaded file as %Current%\123.tmp, which contains a download link of a torrent file pointing to a Trojanized software. It then uses its dropped uTorrent client to silently download the referenced Trojanized software, leading to the download of several components.
As of writing, the downloaded files are detected as follows:
- TROJ_SPAMMER.AA
- WORM_KOOBFACE.AV
- WORM_KOOBFACE.FE
- WORM_KOOBFACE.FH
- WORM_KOOBFACE.FI
- WORM_KOOBFACE.FK
- WORM_KOOBFACE.MJ
- WORM_KOOBFACE.MM
It then executes the downloaded files. As a result, malicious routines of downloaded files are exhibited on the system.
This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Arrival Details
This worm 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 worm drops the following non-malicious file:
- %User Temp%\iexplore.exe - uTorrent client
- %Current%\123.tmp - non-malicious component
(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.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
trr = {malware path and file name}
NOTES:
Upon execution, it sends the following HTTP request to its C&C to download a file:
- http://{C&C}/?action=torgen&v={parameter}s&a=get_tfile
The C&C server may be any of the following:
- {BLOCKED}jkvhhfhflkfiuhieufhieu.com
- {BLOCKED}0jg9glkdnbo43ighbjemh6.com
- {BLOCKED}b49tkfnbk3r0ei5m539tjg.com
- {BLOCKED}0934340tnvnwnv490g9405.com
- {BLOCKED}djcncfjkdfikcndcfndfjcjcfkj.com
- {BLOCKED}fhdskvfjdshfjhfjsahfkjfsajk.com
- {BLOCKED}38sj3n5nt659dl2395k59f.com
- {BLOCKED}bfk2948sk3n5b659259887.com
- {BLOCKED}4k2bf9305k67hb20305696.com
- {BLOCKED}pdjsakcndsjkcbdskjcbdsecjds.com
- {BLOCKED}ndbajxnbndjdkjdokcn827nnnsk.com
- {BLOCKED}wddcjbsjdwdjwopdwojdjjjjjjw.com
- {BLOCKED}fvnw0f38hn09fjnlsn2r9v.com
- {BLOCKED}vxsdhduhdhcbdxhdshcxdhgxdcd.com
- {BLOCKED}5693038f73h50658395020.com
- {BLOCKED}jwqdsajnsjndnsncdsnmcccfasw.com
- {BLOCKED}wdfhsaubxxdwijdididhdhjhdhw.com
- {BLOCKED}xbndskjdsldlodfjcfnapskdjdc.com
- {BLOCKED}bdjduchncdfjhdfujdjddsxbshb.com
- {BLOCKED}bdjduchncdfjhdfujdjddsxbshb.com
It saves the downloaded file as %Current%\123.tmp, which contains a download link of a torrent file pointing to a Trojanized software. It then uses its dropped uTorrent client to silently download the referenced Trojanized software, leading to the download of the following components:
- %User Temp%\{file name of downloaded torrent}\setup.exe – decrypts and executes setup3.cab; executes setup2.cab (also detected as WORM_KOOBFACE.AV)
- %User Temp%\{file name of downloaded torrent}\setup1.cab – downloader of other component binaries (also detected as WORM_KOOBFACE.AV)
- %User Temp%\{file name of downloaded torrent}\setup2.cab – actual installer of the intended software
- %User Temp%\{file name of downloaded torrent}\setup3.cab – decrypts and executes setup1.cab (also detected as WORM_KOOBFACE.AV)
The component setup1.cab then performs the following HTTP request to the C&C to download a dynamic list of component download sites:
- http://{C&C}/.sys.php?action=ldtor&v=1&a={parameter}&id={parameter}&hardid={parameter}
- http://{C&C}/.sys.php?action=fbgen&v=1
It also saves the downloaded list as %Current%\123.tmp.
The downloaded components are all saved using the file name %User Temp%\tx{character}.tmp. As of writing, the downloaded files are detected as follows:
- TROJ_SPAMMER.AA
- WORM_KOOBFACE.AV
- WORM_KOOBFACE.FE
- WORM_KOOBFACE.FH
- WORM_KOOBFACE.FI
- WORM_KOOBFACE.FK
- WORM_KOOBFACE.MJ
- WORM_KOOBFACE.MM
It then executes the downloaded files. As a result, malicious routines of downloaded files are exhibited on the system.
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
Remove malware files dropped/downloaded by WORM_KOOBFACE.AV
TROJ_SPAMMER.AAWORM_KOOBFACE.AV
WORM_KOOBFACE.FE
WORM_KOOBFACE.FH
WORM_KOOBFACE.FI
WORM_KOOBFACE.FK
WORM_KOOBFACE.MJ
WORM_KOOBFACE.MM
Step 3
Identify and terminate files detected as WORM_KOOBFACE.AV
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- 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.
To terminate the malware/grayware process:
- Scan your computer with your Trend Micro product and take note of the name of the malware/grayware/spyware detected.
- Open Windows Task Manager.
• For Windows 2000, XP, and Server 2003 users, press
CTRL+SHIFT+ESC, then click the Processes tab. - In the list of running programs, locate a malware/grayware/spyware file detected earlier.
- Select the detected files, then press either the End Task or the End Process button, depending on the version of Windows you are using.
- Do the same for the remaining detected malware/grayware/spyware files in the list of running programs.
- To check if the malware/grayware/spyware process has been terminated, close Task Manager, and then open it again.
- Close Task Manager.
Step 4
Delete this registry value
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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
- trr = {malware path and file name}
To delete the registry value this malware created:
- Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.
- In the left panel of the Registry Editor window, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
trr = {malware path and file name} - Close Registry Editor.
Step 5
Search and delete this folder
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Please make sure you check the
Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %User Temp%\{file name of downloaded torrent}
To delete the malware/grayware folder:
- Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
- In the Named input box, type:
%User Temp%\{file name of downloaded torrent}
- In the Look In drop-down list, select My Computer, then press Enter.
- Once located, select the folder then press SHIFT+DELETE to permanently delete the folder.
Step 6
Search and delete these files
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There may be some component files that are hidden. Please make sure you check the
Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result. %Current%\123.tmp
%User Temp%\iexplore.exe
To delete malware/grayware component files:
- Search for the following files:
%Current%\123.tmp%User Temp%\iexplore.exe
Note: To do a search for the following files, right-click Start then click Search... or Find..., depending on the version of Windows you are running. For each file to be deleted, type its file name in the Named input box. In the Look In drop-down list, select My Computer, then press Enter. - Once located, select the file then press SHIFT+DELETE to permanently delete the file.
- Repeat the said steps for all files listed.
Step 7
Scan your computer with your Trend Micro product to delete files detected as WORM_KOOBFACE.AV. 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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