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Virus:Win32/Small.R


Virus:Win32/Small.R is a virus that copies itself to the local computer and to removable drives.


What to do now

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft Safety Scanner (http://go.microsoft.com/fwlink/?LinkId=212742). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.

Threat behavior

Virus:Win32/Small.R is a virus that copies itself to the local computer and to removable drives.
Installation
Virus:Win32/Small.R can infect the local computer when a user connects an infected removable drive with Autorun (Autoplay) enabled. When run, it copies itself as the following:
 
%windir%\system\svchost.exe
 
The dropped copy is then run. The registry is modified to run the dropped copy at each Windows start.
 
Adds value: "Userinit"
With data: "userinit.exe,%windir%\system\svchost.exe"
To subkey: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
Spreads Via…
Removable Drives
Virus:Win32/Small.R copies itself to removable drives and creates the following files:
 
<drive:>\recycler\info.exe - copy of Virus:Win32/Small.R
<drive:>\recycler\desktop.ini
<drive:>\autorun.inf
 
The autorun configuration file named 'autorun.inf' points to the file '\recycler\info.exe'. When the removable or networked drive is accessed from another machine supporting the Autorun feature, the malware is launched automatically. The autorun file is identified as Worm:Win32/Autorun!inf.
 
Analysis by Shawn Wang

Symptoms

System Changes
The following system changes may indicate the presence of this malware:
  • The presence of the following files:
    %windir%\system\svchost.exe
    <removable drive:>\recycler\info.exe
  • <removable drive:>\autorun.inf
  • The presence of the following registry modifications:
    Value: "Userinit"
  • With data: "userinit.exe,%windir%\system\svchost.exe"
    In subkey: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

Prevention


Alert level: Severe
First detected by definition: 1.45.287.0
Latest detected by definition: 1.45.287.0 and higher
First detected on: Oct 07, 2008
This entry was first published on: Apr 17, 2009
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • BackDoor.Generic7.MRW (AVG)
  • Trojan.Autorun.PD (BitDefender)
  • Win32/Enfomend.A (CA)
  • Win32/Small.R (ESET)
  • Virus.Win32.Small.r (Kaspersky)
  • Generic BackDoor.j (McAfee)
  • W32/Smalldoor.AOLQ (Norman)
  • Trj/Agent.FQZ (Panda)
  • W32/SillyFDC-H (Sophos)
  • W32.SillyDC (Symantec)
  • WORM_SMALL.HYN (Trend Micro)