TROJ_DLOADR.USBD03AVC
TrojanDownloader:Win32/Fosniw.C (Microsoft); Trojan.Gen (Symantec); Trojan.Win32.Scar.eaiu (Kaspersky); Trojan-Downloader.Win32.Fosniw.c (v) (Sunbelt); Gen:Trojan.Heur.JP.pm0@aaqaf0mG (FSecure)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
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.
TECHNICAL DETAILS
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.
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
d8d4dac4c6c5da9fd4c9d4 = "%User Profile%\Application Data\uwtk.exe"
Other System Modifications
This Trojan deletes the following files:
- %User Profile%\Application Data\uwtk.exe
- %Windows%\fonts\msgothic.ttf
- %Windows%\fonts\msuigoth.ttf
- %Windows%\fonts\MSMINCHO.TTF
- %Windows%\fonts\Gulim.ttf
- %Windows%\fonts\Gulimche.ttf
- %Windows%\fonts\Dotum.ttf
- %Windows%\fonts\Batang.ttf
- %Windows%\fonts\Gungsuh.ttf
- %Windows%\fonts\Simsun.ttf
- %Windows%\fonts\nsimsun.ttf
- %Windows%\fonts\MingLiU.ttf
- %Windows%\fonts\pmingliu.ttf
- %System%\SET2.tmp
- %System%\kbd101b.dll
- %System%\SET4.tmp
- %System%\kbd101c.dll
- %System%\SET6.tmp
- %System%\kbd103.dll
- %System%\SET8.tmp
- %System%\kbd106.dll
- %System%\SETA.tmp
- %System%\kbdjpn.dll
- %System%\SETC.tmp
- %System%\kbdkor.dll
(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uwtk
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
It adds the following registry entries:
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
idt = "201204221727"
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
ver = "1.0.0.6"
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
Location = "d8d4dac4c6c5da9fd4c9d4"
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
pid = "trb1"
HKEY_CURRENT_USER\Software\a0f0f62ea1b1
prj = "4"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uwtk
DisplayName = "Windows IEK uwtk Uninstall"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uwtk
UninstallString = "%User Profile%\Application Data\uwtk.exe uninstall"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Enable = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Size = "a"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
InitHits = "64"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Factor = "14"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "0"
Dropping Routine
This Trojan drops the following files:
- %System%\SET1.tmp
- %System%\SET3.tmp
- %System%\SET5.tmp
- %System%\SET7.tmp
- %System%\SET9.tmp
- %System%\SETB.tmp
- %System%\SET2.tmp
- %System%\SET4.tmp
- %System%\SET6.tmp
- %System%\SET8.tmp
- %System%\SETA.tmp
- %System%\SETC.tmp
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
This report is generated via an automated analysis system.
SOLUTION
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
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
- a0f0f62ea1b1
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
- uwtk
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- CpMRU
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
- d8d4dac4c6c5da9fd4c9d4 = "%User Profile%\Application Data\uwtk.exe"
- In HKEY_CURRENT_USER\Software\a0f0f62ea1b1
- idt = "201204221727"
- In HKEY_CURRENT_USER\Software\a0f0f62ea1b1
- ver = "1.0.0.6"
- In HKEY_CURRENT_USER\Software\a0f0f62ea1b1
- Location = "d8d4dac4c6c5da9fd4c9d4"
- In HKEY_CURRENT_USER\Software\a0f0f62ea1b1
- pid = "trb1"
- In HKEY_CURRENT_USER\Software\a0f0f62ea1b1
- prj = "4"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uwtk
- DisplayName = "Windows IEK uwtk Uninstall"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uwtk
- UninstallString = "%User Profile%\Application Data\uwtk.exe uninstall"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Enable = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Size = "a"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- InitHits = "64"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Factor = "14"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- W2KLpk = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- W2KLpk = "0"
Step 5
Search and delete these files
- %System%\SET1.tmp
- %System%\SET3.tmp
- %System%\SET5.tmp
- %System%\SET7.tmp
- %System%\SET9.tmp
- %System%\SETB.tmp
- %System%\SET2.tmp
- %System%\SET4.tmp
- %System%\SET6.tmp
- %System%\SET8.tmp
- %System%\SETA.tmp
- %System%\SETC.tmp
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DLOADR.USBD03AVC. 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%\Application Data\uwtk.exe
- %Windows%\fonts\msgothic.ttf
- %Windows%\fonts\msuigoth.ttf
- %Windows%\fonts\MSMINCHO.TTF
- %Windows%\fonts\Gulim.ttf
- %Windows%\fonts\Gulimche.ttf
- %Windows%\fonts\Dotum.ttf
- %Windows%\fonts\Batang.ttf
- %Windows%\fonts\Gungsuh.ttf
- %Windows%\fonts\Simsun.ttf
- %Windows%\fonts\nsimsun.ttf
- %Windows%\fonts\MingLiU.ttf
- %Windows%\fonts\pmingliu.ttf
- %System%\SET2.tmp
- %System%\kbd101b.dll
- %System%\SET4.tmp
- %System%\kbd101c.dll
- %System%\SET6.tmp
- %System%\kbd103.dll
- %System%\SET8.tmp
- %System%\kbd106.dll
- %System%\SETA.tmp
- %System%\kbdjpn.dll
- %System%\SETC.tmp
- %System%\kbdkor.dll
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