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The Internet threat alert status is currently normal. At present, no major epidemics or other serious incidents have been recorded by Kaspersky Lab’s monitoring service. Internet threat level: 1

Trojan-Dropper.Win32.Small.du

Detected Feb 02 2004 15:23 GMT
Released Feb 02 2004 15:23 GMT
Published Mar 15 2007 14:48 GMT

Technical Details
Payload
Removal instructions

Technical Details

This Trojan is designed to install and launch other programs on the victim machine. It is a Windows PE EXE file. The size of infected files may vary from 8KB to 19KB.

Payload

Once launched, the Trojan extracts the following files from itself and launches them for execution:

  • %WinDir%\svchost.exe — this file is 11,776 bytes in size. It will be detected by Kaspersky Anti-Virus as Trojan-Spy.Win32.Tofger.ab;
  • %WinDir%\msto32.dll — this file is 3,072 bytes in size. It will be detected by Kaspersky Anti-Virus as Trojan-Spy.Win32.Tofger.aa.

The Trojan also drops the following file, %WinDir%\sysini.ini, which contains the following string:

***Computer was successfully infected***

Once launched, the Trojan registers itself in the system registry:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
"Online Service" = "%WinDir%\svchost.exe"

This ensures that the Trojan will be launched each time Windows is booted on the victim machine.


Removal instructions

If your computer does not have an up-to-date antivirus, or does not have an antivirus solution at all, follow the instructions below to delete the malicious program:

  1. Use Task Manager to terminate the Trojan process.
  2. Delete the original Trojan file (the location will depend on how the program originally penetrated the victim machine).
  3. Delete the files created by the Trojan:
    %WinDir%\svchost.exe
    %WinDir%\msto32.dll
    %WinDir%\sysini.ini
  4. Delete the following system registry key parameter:
    [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
    "Online Service" = "%WinDir%\svchost.exe"
  5. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).

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Trojan-Dropper

Trojan-Dropper programs are designed to secretly install malicious programs built into their code to victim computers.

This type of malicious program usually save a range of files to the victim’s drive (usually to the Windows directory, the Windows system directory, temporary directory etc.), and launches them without any notification (or with fake notification of an archive error, an outdated operating system version, etc.).

Such programs are used by hackers to:

  • secretly install Trojan programs and/or viruses
  • protect known malicious programs from being detected by antivirus solutions; not all antivirus programs are capable of scanning all the components inside this type of Trojans.

Other versions

Aliases

Trojan-Dropper.Win32.Small.du (Kaspersky Lab) is also known as:

  • TrojanDropper.Win32.Small.du (Kaspersky Lab)
  • Trojan: MultiDropper-GP.a (McAfee)
  • Troj/Tofger-A (Sophos)
  • Trojan.Dropper.Small-44 (ClamAV)
  • Trj/Tofger.B (Panda)
  • W32/Virus_Dropper!2abe (FPROT)
  • PWS:Win32/Tofger (MS(OneCare))
  • Trojan.MulDrop.638 (DrWeb)
  • Win32/TrojanDropper.Small.CO trojan (Nod32)
  • Trojan.Dropper.Small.CO (BitDef7)
  • Trojan.Tofger.A (VirusBuster)
  • Win32:Small-MFK [Trj] (AVAST)
  • Trojan.Win32.Explodus (Ikarus)
  • Dropper.Small.EL (AVG)
  • TR/Tofger.3 (AVIRA)
  • Infostealer.Tarno.B (NAV)
  • W32/Tofger.A (Norman)
  • MultiDropper-GP.a (NAI)
  • TROJ_SMALL.CO (PCCIL)
  • Dropper.Small.alb (Rising)
  • TROJ_SMALL.CO (TrendMicro)