Win32/Yeltminky is a family of worms that spreads by making copies of itself on all available drives and creating an autorun.inf file to execute that copy.

What to do now

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

For more information on antivirus software, see

Additional remediation instructions for Win32/Yeltminky

This threat may make lasting changes to a computer's configuration that are NOT restored by detecting and removing this threat. For more information on returning an infected computer to its pre-infected state, please see the following articles:

Threat behavior

Win32/Yeltminky is a family of worms that spreads by making copies of itself on all available drives and creating an autorun.inf file to execute that copy.


When executed the malware makes a copy of itself in one of the following locations:

  • %USERPROFILE%\<file name>.exe
  • %windir%\fonts\ < file name> .fon

It may also copy itself to a secondary location.

The file name used, and the secondary location it copies itself to, is supplied as part of configuration data stored in the malware file, for example:

  • %USERPROFILE%\auto.exe
  • %ProgramFiles%\common files\auto.exe

The malware also drops a DLL component to one of the following locations:

  • %USERPROFILE%\<random file name>.drv
  • %USERPROFILE%\<random file name>.fon

The file name is randomly generated and the file extension may vary, for example:

  • %USERPROFILE%\jmfxs.drv
  • %windir%\fonts\evngj.fon

The DLL component may then drop a driver component with a random name in one of the following locations:

  • %USERPROFILE%\<random file name>
  • %windir%\fonts\<random file name>.fon

Once the driver is loaded, the file is deleted.

The worm modifies the following registry entries to ensure that its copy executes at each Windows start:

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
Sets value: "auto"
With data: "%ProgramFiles%\common files\auto.exe"

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
Sets value: "SysAnti"
With data: "%ProgramFiles%\common files\sysanti.exe"

The malware can also contact a remote host to provide notification of a successful infection. The host URL is provided in the configuration data.

Spreads via...

Networked and removable drives

The malware checks for all drives available from A: to Z:, and if found, it makes a copy of itself in the root directory of the drive and creates a corresponding autorun.inf file to ensure its execution.

The file name the malware uses to copy itself to is provided in configuration data stored in the malware, for example:

  • <Drive>:\sysanti.exe
  • <Drive>:\autorun.inf

Downloads and executes arbitrary files

The malware connects to a remote host, where it obtains a list of files to download and execute.

It then proceeds to download and execute each file. The downloaded files are written to the %Temp% directory.

Terminates processes

The malware carries a list of processes which it terminates if found executing on the infected computer. It does this by dropping the DLL component which is injected into a newly created "svchost.exe" process (the DLL component in turn drops and installs the driver).

The following is a non-exhaustive list of processes that are targeted:

  • 360deepscan
  • 360hotfix
  • 360rp
  • 360rpt
  • 360Safe
  • 360safebox
  • 360sd
  • 360tray
  • adam
  • AgentSvr
  • AntiArp
  • AppSvc32
  • arvmon
  • AutoGuarder
  • autoruns
  • avgrssvc
  • AvMonitor
  • avp
  • CCenter
  • ccSvcHst
  • DSMain
  • egui
  • ekrn
  • FileDsty
  • findt2005
  • FTCleanerShell
  • HijackThis
  • IceSword
  • iparmo
  • Iparmor
  • IsHelp
  • isPwdSvc
  • kabaload
  • KaScrScn.SCR
  • KASMain
  • KASTask
  • KAV32
  • KAVSetup
  • KAVStart
  • killhidepid
  • KISLnchr
  • kissvc
  • KMailMon
  • KMFilter
  • KPFW32
  • KPFW32X
  • KPFWSvc
  • KRepair.COM
  • krnl360svc
  • KsLoader
  • kswebshield
  • KVCenter.kxp
  • KvDetect
  • kvfw
  • KvfwMcl
  • KVMonXP.kxp
  • KVMonXP_1.kxp
  • kvol
  • kvolself
  • KvReport.kxp
  • KVScan.kxp
  • KVSrvXP
  • KVStub.kxp
  • kvupload
  • kvwsc
  • KvXP.kxp
  • KvXP_1.kxp
  • KWatch
  • KWatch9x
  • KWatchX
  • LiveUpdate360
  • loaddll
  • MagicSet
  • mcconsol
  • mmqczj
  • mmsk
  • NAVSetup
  • nod32krn
  • nod32kui
  • PFW
  • PFWLiveUpdate
  • Ras
  • Rav
  • RavCopy
  • RavMon
  • RavMonD
  • RavStore
  • RavStub
  • ravt08
  • RavTask
  • RegClean
  • RegEx
  • rfwcfg
  • RfwMain
  • rfwolusr
  • rfwProxy
  • rfwsrv
  • RsAgent
  • Rsaupd
  • RsMain
  • rsnetsvr
  • RSTray
  • runiep
  • safebank
  • safeboxTray
  • safelive
  • scan32
  • ScanFrm
  • shcfg32
  • smartassistant
  • SmartUp
  • SREng
  • SREngPS
  • SuperKiller
  • symlcsvc
  • syscheck
  • Syscheck2
  • SysSafe
  • ToolsUp
  • TrojanDetector
  • Trojanwall
  • TrojDie.kxp
  • UIHost
  • UmxAgent
  • UmxAttachment
  • UmxCfg
  • UmxFwHlp
  • UmxPol
  • UpLive
  • WoptiClean
  • ZhuDongFangYu
  • zxsweep

The malware also checks for the following substrings in a process in order to terminate it:

  • AutoRun
  • IceSword
  • NOD32
  • SysCheck
  • 冰刃
  • 杀软
  • 诺顿
  • 卡巴
  • 毒霸
  • 江民
  • 清道夫
  • 瑞星
  • 木马
  • 病毒
  • 杀毒
  • 绿鹰
  • 专杀
  • 组策略
  • 防火墙
  • 安全卫士
  • 清理专
  • 云安全

Modifies system settings

The malware creates the following registry entry:

In subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options

and uses it to prevent the execution of the following files:

  • 360hotfix.exe
  • 360rpt.exe
  • 360Safe.exe
  • 360safebox.exe
  • 360tray.exe
  • adam.exe
  • AgentSvr.exe
  • AntiArp.exe
  • AppSvc32.exe
  • arvmon.exe
  • AutoGuarder.exe
  • autoruns.exe
  • avgrssvc.exe
  • AvMonitor.exe
  • avp.exe
  • CCenter.exe
  • ccSvcHst.exe
  • FileDsty.exe
  • findt2005.exe
  • FTCleanerShell.exe
  • HijackThis.exe
  • IceSword.exe
  • iparmo.exe
  • Iparmor.exe
  • IsHelp.exe
  • isPwdSvc.exe
  • kabaload.exe
  • KaScrScn.SCR
  • KASMain.exe
  • KASTask.exe
  • KAV32.exe
  • KAVDX.exe
  • KAVPFW.exe
  • KAVSetup.exe
  • KAVStart.exe
  • killhidepid.exe
  • KISLnchr.exe
  • KMailMon.exe
  • KMFilter.exe
  • KPFW32.exe
  • KPFW32X.exe
  • KPFWSvc.exe
  • KRepair.COM
  • KsLoader.exe
  • KVCenter.kxp
  • KvDetect.exe
  • kvfw.exe
  • KvfwMcl.exe
  • KVMonXP.kxp
  • KVMonXP_1.kxp
  • kvol.exe
  • kvolself.exe
  • KvReport.kxp
  • KVScan.kxp
  • KVSrvXP.exe
  • KVStub.kxp
  • kvupload.exe
  • kvwsc.exe
  • KvXP.kxp
  • KvXP_1.kxp
  • KWatch.exe
  • KWatch9x.exe
  • KWatchX.exe
  • LiveUpdate360.exe
  • loaddll.exe
  • MagicSet.exe
  • mcconsol.exe
  • mmqczj.exe
  • mmsk.exe
  • NAVSetup.exe
  • nod32krn.exe
  • nod32kui.exe
  • PFW.exe
  • PFWLiveUpdate.exe
  • QHSET.exe
  • Ras.exe
  • Rav.exe
  • RavCopy.exe
  • RavMon.exe
  • RavMonD.exe
  • RavStore.exe
  • RavStub.exe
  • ravt08.exe
  • RavTask.exe
  • RegClean.exe
  • RegEx.exe
  • rfwcfg.exe
  • RfwMain.exe
  • rfwolusr.exe
  • rfwProxy.exe
  • rfwsrv.exe
  • RsAgent.exe
  • Rsaupd.exe
  • RsMain.exe
  • rsnetsvr.exe
  • RSTray.exe
  • runiep.exe
  • safebank.exe
  • safeboxTray.exe
  • safelive.exe
  • scan32.exe
  • ScanFrm.exe
  • shcfg32.exe
  • smartassistant.exe
  • SmartUp.exe
  • SREng.exe
  • SREngPS.exe
  • symlcsvc.exe
  • syscheck.exe
  • Syscheck2.exe
  • SysSafe.exe
  • ToolsUp.exe
  • TrojanDetector.exe
  • Trojanwall.exe
  • TrojDie.kxp
  • UIHost.exe
  • UmxAgent.exe
  • UmxAttachment.exe
  • UmxCfg.exe
  • UmxFwHlp.exe
  • UmxPol.exe
  • UpLive.exe
  • WoptiClean.exe
  • zxsweep.exe

Note: This list is not exhuastive.

Modifies Hosts file

The malware modifies the Hosts file in an attempt to prevent the affected user from accessing certain antivirus websites.

The list of sites it blocks access to is carried by the malware, or obtained from a remote host, which is specified in the configuration data carried by the malware.

Below are some examples of the websites it attempts to block access to:


Modifies browser settings

 Win32/Yeltminky can also modify the browser start page to point to a particular URL. The URL is provided in the configuration data carried by the malware.

Analysis by Ray Roberts


System changes
The following system changes may indicate the presence of this malware:
  • The presence of the following registry modifications:

    In subkey: HKCU\Software\Microsoft\Internet Explorer\Main
    Sets value: "Start Page"
    With data: ""

    In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    Sets value: "auto"
    With data: "%ProgramFiles%\common files\auto.exe"

    In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    Sets value: "SysAnti"
    With data: "%ProgramFiles%\common files\sysanti.exe"



Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to webpages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites. Instructions on how to download the latest versions of some common software is available from the following:

You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see

Limit user privileges on the computer

Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.

You can configure UAC in your computer to meet your preferences:

Use caution when opening attachments and accepting file transfers

Exercise caution with email and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.

Use caution when clicking on links to webpages

Exercise caution with links to webpages that you receive from unknown sources, especially if the links are to a webpage that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a webpage with harmful content.

Avoid downloading pirated software

Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.

Protect yourself from social engineering attacks

While attackers may attempt to exploit vulnerabilities in hardware or software to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.

Use strong passwords

Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least eight characters, and combines letters, numbers, and symbols. For more information, see

Alert level: Severe
This entry was first published on: Aug 25, 2010
This entry was updated on: Mar 13, 2012

This threat is also detected as:
No known aliases