Encyclopedia entry
Updated: Apr 17, 2011 | Published: Aug 25, 2010
Aliases
Alert Level (?)
Severe
Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.
Updated: Apr 17, 2011 | Published: Aug 25, 2010
Aliases
-
Mal_Otorun9 (Trend Micro)
- Trojan.Win32.Buzus.cqyx (Kaspersky)
- Trojan Horse (Symantec)
Alert Level (?)
Severe
Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.
| Detection initially created: Definition: 1.121.1275.0 Released: Mar 10, 2012 |
Summary
Worm:Win32/Autorun.TW is a worm - a self-propagating program that can spread itself from one computer to another. Worms may spread themselves via a variety of different channels in order to compromise new computers. Variants of Worm:Win32/Autorun usually spread using methods that include, but may not be limited to, copying themselves to removable or network drives, and placing an autorun.inf file in the root directory of each affected drive in an attempt to ensure that the worm is run when the removable drive is attached, or the network drive is visited from a remote system supporting the Autorun feature.
Symptoms
System changes
The following system changes may indicate the presence of this malware:
- The presence of the following files: %programfiles%\common files\sytvsm.exe
- The presence of the following registry modifications:
c:\documents and settings\administrator\agdai.drv
c:\documents and settings\administrator\jrwnf
c:\documents and settings\administrator\nbcxd.drv
c:\documents and settings\administrator\qtaop
Adds value: "Sytvsm"
With data: "c:\program files\common files\sytvsm.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
With data: "c:\program files\common files\sytvsm.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
Adds value: "Start Page"
With data: "http://www.xinfeng.net"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Main
With data: "http://www.xinfeng.net"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Main
Technical Information (Analysis)
Worm:Win32/Autorun.TW is a worm - a self-propagating program that can spread itself from one computer to another. Worms may spread themselves via a variety of different channels in order to compromise new computers. Variants of Worm:Win32/Autorun usually spread using methods that include, but may not be limited to, copying themselves to removable or network drives, and placing an autorun.inf file in the root directory of each affected drive in an attempt to ensure that the worm is run when the removable drive is attached, or the network drive is visited from a remote system supporting the Autorun feature.
Installation
When executed, Worm:Win32/Autorun.TW copies itself to %programfiles%\common files\sytvsm.exe.
The malware modifies the following registry entries to ensure that its copy executes at each Windows start:
Adds value: "Sytvsm"
With data: "c:\program files\common files\sytvsm.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
With data: "c:\program files\common files\sytvsm.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
The malware creates files on an affected computer using variable file names, for example:
- c:\documents and settings\administrator\agdai.drv - detected as Worm:Win32/Autorun.DM!dll
- c:\documents and settings\administrator\jrwnf - detected as Worm:Win32/Autorun.DM!dll
- c:\documents and settings\administrator\nbcxd.drv - detected as Worm:Win32/Autorun.DM!dll
- c:\documents and settings\administrator\qtaop - detected as Worm:Win32/Autorun.DM!dll
Spreads via…
Removable and network drives
Worm:Win32/Autorun.TW may copy itself to network and/or removable drives. It may also place an autorun.inf file in the root directory of the targeted drive. Such autorun.inf files contain execution instructions for the operating system, so that when the network and/or removable drive is accessed from another computer supporting the Autorun feature, the malware is launched automatically. This is particularly common malware behavior, generally utilized in order to spread malware from computer to computer. It should also be noted that autorun.inf files on their own are not necessarily a sign of infection, as they are used by legitimate programs and installation CDs.
Note: this worm was not observed to write an executable or create an autorun.inf file on a targeted drive in our automated testing environment. This may be because it does not begin spreading immediately, or because it may need to be commanded to spread from a remote source.
Note: this worm was not observed to write an executable or create an autorun.inf file on a targeted drive in our automated testing environment. This may be because it does not begin spreading immediately, or because it may need to be commanded to spread from a remote source.
Payload
Modifies browser settings
Worm:Win32/Autorun.TW modifies the affected computer's browser settings by making the following changes to the registry:
- The malware changes the start page for Internet Explorer to http://www.xinfeng.net by making the following registry modification:
Adds value: "Start Page"
With data: "http://www.xinfeng.net"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Main
Contacts remote host
The malware may contact a remote host at web.usea51la.cn using port 80. Commonly, malware may contact a remote host for the following purposes:
- To report a new infection to its author
- To receive configuration or other data
- To download and execute arbitrary files (including updates or additional malware)
- To receive instruction from a remote attacker
- To upload data taken from the affected computer
This malware description was produced and published using our automated analysis system's examination of file SHA182a9bda95f164e198adb31a0e2b895d9ce357204.
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