How to completely remove Sirefef Trojan (Virus Removal Guide)

The Sirefef trojan is a dangerous threat that has been circulating for several years. In the time that Sirefef has been in the wild there have been a number of revisions, with modifications to its functionality, infection strategy and its persistence mechanisms on an infected machine. However, the core purpose has remained: to assume full control of the machine by adding it to the Sirefef botnet and to monetize the new asset by downloading additional malware.
[Image: Trojan Sirefef virus]
Primarily, Trojan Sirefef is a kernel-mode rootkit, similar in ethos to the TDL family of rootkits. It uses advanced techniques to hide its presence, is capable of functioning on both 32 and 64-bit flavors of Windows from a single installer, contains aggressive self defense functionality and acts as a sophisticated delivery platform for other malware.

Trojan Sirefef remains hidden on an infected machine while downloading more visible components that generate revenue for the botnet owners. Currently the downloaded malware is mostly aimed at sending spam and carrying out click fraud, but previously the botnet has been instructed to download other malware and it is likely that this will be the case again in the future.

Trojan Sirefef has been observed being distributed by exploits and programs that promote software-piracy, such as ‘keygens’ and ‘cracks’ (programs designed to bypass software licensing).

Variants of Trojan Sirefef may also be dropped or installed by other malware, including variants of the Trojan:Win32/Necurs family.

In the wild, newer Trojan Sirefef variants have been observed dropping the following two files to a chosen directory, for example, C:\recycler\s\:

  • “@” – this file contains information that Sirefef can use to find other infected computers
  • “n” – this file contains the malicious code for peer-to-peer (P2P) communication

These newer variants then make the following changes to the registry to ensure that Sirefef runs each time you start your computer:

In subkey: HKLM\Software\Classes\clsid\{5839fca9-774d-42a1-acda-d6a79037f57f}\InprocServer32
Modifies value: “(Default)”
From data: “\wbem\wbemess.dll”
With data: “” (for example, “c:\recycler\s\\n”)

In the wild, the Trojan Sirefef may be detected by antivirus products as:

  • Win64/Sirefef.W (ESET)
  • Sirefef.BX (AVG)
  • Win64/Sirefef.AE (ESET)
  • Trojan.Sirefef.B (Ikarus)
  • Sirefef.C (McAfee)
  • Win32/Sirefef.gen!C (Kaspersky)
  • Troj/Sirefef-AQ (Sophos)
  • Trojan.Sirefef!inf2 (Symantec)
  • Trojan:Win32/Sirefef (Microsoft)
  • W32/Troj_Generic.UUZF (Norman)
  • Trojan:Win64/Sirefef (VirusBuster)
  • Trojan horse Crypt.AQLW (AVG)
  • TR/Sirefef.BV.2 (Avira)
  • Trojan.Sirefef.BV (BitDefender)
  • BackDoor.Maxplus.3710 (Dr.Web)
  • Trojan.Sirefef.C (Ikarus)
  • Sirefef.B (McAfee)
  • Virus:Win32/Sirefef.R (Sophos)
  • Trojan.Sirefef!gen3 (Norton)
  • TrojanDropper:Win32/Sirefef.A!dll (Trend Micro)

Trojan Sirefef is a dangerous threat that uses advanced stealth techniques in order to hinder its detection and removal. As a consequence of being infected with this threat, you may need to repair and reconfigure some Windows security features.

Because the malware removal process for the Sirefef trojan is very complex, we recommend that you backup your personal files and folders before starting to remove this infection.

How to remove Sirefef Trojan virus (Virus Removal Guide)

This malware removal guide may appear overwhelming due to the amount of the steps and numerous programs that are being used. We have only written it this way to provide clear, detailed, and easy to understand instructions that anyone can use to remove malware for free.
Please perform all the steps in the correct order. If you have any questions or doubt at any point, STOP and ask for our assistance.

STEP 1:  Use ESETSirfefCleaner tool to remove Sirefef Trojan

In this first step, we will use the ESETSirefefCleaner tool to remove the Sirefef Trojan from your computer.

  1. You can download ESETSirefefCleaner from the below link.
    ESETSIREFEFCLEANER DOWNLOAD LINK(This link will automatically download Kaspersky TDSSKiller on your computer.)

    Unable to download “ESETSirefefCleaner.exe contained a virus and was deleted”.
    More recent variants of Sirefef might prevent you from downloading this removal tool. If you cannot download the tool, follow the steps below:

    1. Click Start → Computer → Local Disk (C:) → Program Files.
    2. Right-click the Windows Defender folder and select Rename from the context menu.
    3. Add a unique variation to the filename, such as .old (for example, Windows Defender.old).
    4. Click the link above to download the ESETSirefefCleaner tool.When the download is complete, make sure to rename the Windows Defender folder back to its original filename before running the ESET SirefefCleaner tool.
  2. Double-click on ESETSirefefCleaner.exe to start this utility. You may be presented with an User Account Control pop-up asking if you want to allow this to make changes to your device. If this happens, you should click “Yes” to continue.
  3. The message “Win32/Sirefef.EV found in your system” will be displayed if an infection is found. To remove Sirefef Trojan from your computer, press the Y key on your keyboard
    ESETSirefefCleaner virus detected
  4. Once the tool has run, you will be prompted to restore system services after you restart your computer. Press Y on your keyboard to restore system services and restart your computer.
    ESETSirefefCleaner Press Y to remove malware
  5. Once your computer has restarted, if you are presented with a security notification click Yes or Allow. and then continue wit the next step.

STEP 2: Use RKill to stop the Sirefef Trojan malicious processes

RKill is a program that will attempt to terminate all malicious processes associated with Sirefef Trojan, so that we will be able to perform the next step without being interrupted by this malicious software.

Because this utility will only stop Sirefef Trojan running process and does not delete any files, after running it you should not reboot your computer as any malware processes that are configured to start automatically will just be started again.
  1. You can download Rkill from the below link.
    RKILL DOWNLOAD LINK (his link will open a new web page from where you can download “RKill”)
  2. Double click on Rkill program to stop the malicious programs from running.
    Start the Rkill program
  3. RKill will now start working in the background, please be patient while this utiltiy looks for malicious process and tries to end them.
    Rkill Running
  4. When the Rkill tool has completed its task, it will generate a log. Do not reboot your computer after running RKill as the malware programs will start again.
    Rkill Program


STEP 3: Scan your computer with Malwarebytes Anti-Malware to remove Sirefef Trojan

Malwarebytes Anti-Malware is a powerful on-demand scanner which should remove the Sirefef Trojan virus from your machine. It is important to note that Malwarebytes Anti-Malware will run alongside antivirus software without conflicts.

  1. You can download download Malwarebytes Anti-Malware from the below link.
    MALWAREBYTES ANTI-MALWARE DOWNLOAD LINK (This link open a new page from where you can download “Malwarebytes Anti-Malware”)
  2. When Malwarebytes has finished downloading, double-click on the “mb3-setup-consumer” file to install Malwarebytes Anti-Malware on your computer.
    Malwarebytes installer
    You may be presented with an User Account Control pop-up asking if you want to allow Malwarebytes to make changes to your device. If this happens, you should click “Yes” to continue with the installation.
    Malwarebytes User Account Control Prompt
  3. When the Malwarebytes installation begins, you will see the Malwarebytes Setup Wizard which will guide you through the installation process.
    Setup Malwarebytes installer
    To install Malwarebytes Anti-Malware on your machine, keep following the prompts by clicking the “Next” button.
    Completing the Malwarebytes Setup Wizard
  4. Once installed, Malwarebytes will automatically start and update the antivirus database. To start a system scan you can click on the “Scan Now” button.
    Perform a system scan with Malwarebytes
  5. Malwarebytes Anti-Malware will now start scanning your computer for malicious programs.
    This process can take a few minutes, so we suggest you do something else and periodically check on the status of the scan to see when it is finished.
    Malwarebytes scanning for malware
  6. When the scan has completed, you will be presented with a screen showing the malware infections that Malwarebytes Anti-Malware has detected.
    To remove the malicious programs that Malwarebytes has found, click on the “Quarantine Selected” button.
    Malwarebytes Quarantine Selected
  7. Malwarebytes Anti-Malware will now quarantine all the malicious files and registry keys that it has found.
    To complete the malware removal process, Malwarebytes may ask you to restart your computer.
    Malwarebytes removing malware from computer
    When the malware removal process is complete, you can close Malwarebytes Anti-Malware and continue with the rest of the instructions.

STEP 4: Double-check for malicious programs with HitmanPro

HitmanPro can find and remove malware, adware, bots, and other threats that even the best antivirus suite can oftentimes miss. HitmanPro is designed to run alongside your antivirus suite, firewall, and other security tools.

  1. You can download HitmanPro from the below link:
    HITMANPRO DOWNLOAD LINK (This link will open a new web page from where you can download “HitmanPro”)
  2. When HitmanPro has finished downloading, double-click on the “hitmanpro” file to install this program on your computer.
    HitmanPro icon
    You may be presented with an User Account Control pop-up asking if you want to allow HitmanPro to make changes to your device. If this happens, you should click “Yes” to continue with the installation.
    HitmanPro User Account Control Pop-up
  3. When the program starts you will be presented with the start screen as shown below. Now click on the Next button to continue with the scan process.
    HitmanPro setup process
  4. HitmanPro will now begin to scan your computer for malware.
    HitmanPro scanning for Sirefef Trojan virus
  5. When it has finished it will display a list of all the malware that the program found as shown in the image below. Click on the “Next” button, to remove malware.
    HitmanPro detected malware
  6. Click on the “Activate free license” button to begin the free 30 days trial, and remove all the malicious files from your computer.
    Activate HitmanPro to remove malware
    When the process is complete, you can close HitmanPro and continue with the rest of the instructions.

(OPTIONAL) STEP 5: Use Zemana AntiMalware Portable to remove Sirefef Trojan

Zemana AntiMalware Portable is a free utility that will scan your computer for the Sirefef Trojan and other malicious programs.
This step should be performed only if your issues have not been solved by the previous steps.
  1. You can download Zemana AntiMalware Portable from the below link:
    ZEMANA ANTIMALWARE PORTABLE DOWNLOAD LINK (This link will open a new web page from where you can download “Zemana AntiMalware Portable”)
  2. Double-click on the file named “Zemana.AntiMalware.Portable” to perform a system scan with Zemana AntiMalware Free.
    Zemana AntiMalware portable
    You may be presented with a User Account Control dialog asking you if you want to run this program. If this happens, you should click “Yes” to allow Zemana AntiMalware to run.
    Zemana AntiMalware User Account Control
  3. When Zemana AntiMalware will start, click on the “Scan” button to perform a system scan.
    Zemana AntiMalware Free Scan
  4. Zemana AntiMalware will now scan your computer for malicious programs. This process can take up to 10 minutes.
    Zemana AntiMalware scanning for virus
  5. When Zemana has finished finished scanning it will show a screen that displays any malware that has been detected. To remove all the malicious files, click on the “Next” button.
    Zemana AntiMalware Removing Sirefef Trojan Virus
    Zemana AntiMalware will now start to remove all the malicious programs from your computer.
Your computer should now be free of the Sirefef Trojan. If you are still experiencing problems while trying to remove Sirefef Trojan from your machine, you can ask for help in our Malware Removal Assistance forum.
How to Stay Safe Online

Here are 10 basic security tips to help you avoid malware and protect your device:

  1. Use a good antivirus and keep it up-to-date.

    Shield Guide

    It's essential to use a good quality antivirus and keep it up-to-date to stay ahead of the latest cyber threats. We are huge fans of Malwarebytes Premium and use it on all of our devices, including Windows and Mac computers as well as our mobile devices. Malwarebytes sits beside your traditional antivirus, filling in any gaps in its defenses, and providing extra protection against sneakier security threats.

  2. Keep software and operating systems up-to-date.

    updates-guide

    Keep your operating system and apps up to date. Whenever an update is released for your device, download and install it right away. These updates often include security fixes, vulnerability patches, and other necessary maintenance.

  3. Be careful when installing programs and apps.

    install guide

    Pay close attention to installation screens and license agreements when installing software. Custom or advanced installation options will often disclose any third-party software that is also being installed. Take great care in every stage of the process and make sure you know what it is you're agreeing to before you click "Next."

  4. Install an ad blocker.

    Ad Blocker

    Use a browser-based content blocker, like AdGuard. Content blockers help stop malicious ads, Trojans, phishing, and other undesirable content that an antivirus product alone may not stop.

  5. Be careful what you download.

    Trojan Horse

    A top goal of cybercriminals is to trick you into downloading malware—programs or apps that carry malware or try to steal information. This malware can be disguised as an app: anything from a popular game to something that checks traffic or the weather.

  6. Be alert for people trying to trick you.

    warning sign

    Whether it's your email, phone, messenger, or other applications, always be alert and on guard for someone trying to trick you into clicking on links or replying to messages. Remember that it's easy to spoof phone numbers, so a familiar name or number doesn't make messages more trustworthy.

  7. Back up your data.

    backup sign

    Back up your data frequently and check that your backup data can be restored. You can do this manually on an external HDD/USB stick, or automatically using backup software. This is also the best way to counter ransomware. Never connect the backup drive to a computer if you suspect that the computer is infected with malware.

  8. Choose strong passwords.

    lock sign

    Use strong and unique passwords for each of your accounts. Avoid using personal information or easily guessable words in your passwords. Enable two-factor authentication (2FA) on your accounts whenever possible.

  9. Be careful where you click.

    cursor sign

    Be cautious when clicking on links or downloading attachments from unknown sources. These could potentially contain malware or phishing scams.

  10. Don't use pirated software.

    Shady Guide

    Avoid using Peer-to-Peer (P2P) file-sharing programs, keygens, cracks, and other pirated software that can often compromise your data, privacy, or both.

To avoid potential dangers on the internet, it's important to follow these 10 basic safety rules. By doing so, you can protect yourself from many of the unpleasant surprises that can arise when using the web.

6 thoughts on “How to completely remove Sirefef Trojan (Virus Removal Guide)”

  1. Your tutorial worked great and hitman pro did find 1 item that the other scanners failed to detect. All in all I would say this was a success aside for one thing; sirefef wiped out all my windows firewall settings and I have no clue how to restore that back the way it was before the virus. I am running Windows 8 pro x64 and even after several google attempts, I still can find no useful information on repairing that damage. I suspect a system restore point may have done the trick however I don’t use restore because I dislike having HDD space eaten up for long periods of time for no apparent reason. I guess that will teach me for being too cheap to invest in an external HD and imaging a backup of my primary partition after a full install. At least if need be I can always reinstall windows without losing anything because all my important sh!t’s on another partition. Restoring an image of a partition would also have taken far less time than installing and using all these scanners. Was worth a shot though. I’m just going to give in and spend that 100 bucks and never worry about this crap again. If there’s one thing all viruses hate, it’s format c: /q !!

  2. Hello,

    Lets run a scan with ESETSirefefCleaner tool:
    1.Click the link below to download the ESETSirefefCleaner tool, and save the file to your Desktop : http://download.eset.com/special/ESETSirefefCleaner.exe
    2.From your Desktop, double-click ESETSirefefCleaner utility. If security notifications appear, click Continue or Run.
    3.The message “Win32/Sirefef.EV found in your system” will be displayed If an infection is found. Press Y on your keyboard to remove the infection.
    4.Once the tool has run, you will be prompted to restore system services after you restart your computer. Press Y on your keyboard to restore system services and restart your computer.
    5.Once your computer has restarted, if you are presented with a security notification click Yes or Allow.
    6.Click Yes at the ESET Services Repair tool window.
    7.Once the ESET Services Repair process is complete, you will again be prompted to restart your computer, to do so click Yes.

    Stay safe!

  3. This worked. Hitman Pro provided a very good explanation of the condition of the Windows file services.exe. So what I did when I finished the above is restore to an earlier time in order to get the Windows file back. Without doing this, I was unable to run the Windows firewall, since it was disabled at startup and was unable to turn it on.
    Thank you for posting this procedure. Thought I was going to have to start back with an image copy of Windows 7 and start over.

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