Geek's Advice

IRFK ransomware maliciously encrypts files on a computer, then tries to extort the user

IRFK ransomware virus is part of the infamous STOP/DJVU ransomware family. Once it infects the target computer, it encrypts all data on it using Salsa20+RSA-2048 encryption algorithm and appends .irfk extension to each affected file. To illustrate, a file that’s been originally called 1.jpg becomes 1.irfk after being infected. The virus also drops ransom note called _readme.txt in every folder while damaging victim’s data. The note introduces cybercriminals intentions and explains that all data was locked with intention to extort the computer user. In order to recover all data, the victim is asked to pay a ransom to get IRFK decryption tool.

IRFK ransomware was created by a cybercriminal gang that’s been releasing similar viruses since 2019. The aim of this malware is to lock files on the target system using encryption algorithms. While encryption itself isn’t malicious, the offenders put it to bad use to extort the computer users. After encrypting all data on the computer, the virus leaves ransom notes suggesting that the victim needs to pay up in order to recover files. The note specifies that pictures, databases, videos, documents, projects and archives were locked and in order to get further instructions on how to pay the criminals, the victim needs to write to attackers via manager@mailtemp.ch and helprestoremanager@airmail.cc (both are included in the _readme.txt file).

Further instructions in the ransom note suggest that the price of data decryption depends upon specific timeframe. According to the note, the attackers are willing to provide 50% discount for those victims who write to the attackers within 72 hours (3 days) starting from the infection timestamp. This means the decryption tool and key costs $490. If delayed any longer, there will be no discount and the victim needs to pay full price, which is $980.

Futhermore, to convince the victim to pay up, the ransom note suggests sending one small file for test decryption. The victim would receive a decrypted version, but only if the file sent contains no valuable information.

When contacted via email, the cybercriminals will explain that the ransom needs to be paid in cryptocurrency. They will also give instructions how cryptocurrency can be purchased and transferred to their virtual wallet address. The only reason why the crooks accept this form of payment is because it prevents law enforcement agencies from tracking them down.

Information security experts and FBI advise against ransom payments. In many cases, victims end up not recovering their files despite paying the ransom; moreover, STOP/DJVU variants are known to install information-stealing Trojans like VIDAR or AZORULT on infected systems, which means they can use collected data to blackmail you further. Besides, paying simply fuels this illegal business model. According to reports, operators of such malware collect millions in USD annually, and such large sums attracts other people to join in. Think of it this way – the more money criminals collect, the more skilled developers they can employ and they can also expand their distributors’ network further.

The most important thing to do if you’ve fallen victim to a crypto-virus attack is to remove malware from your computer immediately. To remove IRFK ransomware virus, we recommend using a robust antivirus software. If you do not have one yet, consider using INTEGO Antivirus which can detect nearly 100% of all malware and also provide you with real-time protection. Additionally, we suggest downloading RESTORO, a tool that can repair virus damage on Windows OS files affected by malware. Please see the guidelines below this article on how to boot your computer in Safe Mode with Networking so that all threats could be eradicated safely.

Ransomware Summary

Name	IRFK Ransomware Virus
Type	Ransomware; Crypto-malware; Virtual Extortion Virus
Family	STOP/DJVU
Encryption type	RSA 2048 + Salsa20
Previous versions	VYIA, QBAA, FOPA, VTYM, KQGS, XCBG, BPQD (find full list here)
Version	346th
Extension	.irfk
Cybercriminal emails	manager@mailtemp.ch, helprestoremanager@airmail.cc
Additional malware dropped	Azorult or Vidar Trojan
Damage	The ransomware infects computers by stealth as it typically arrives in a form of a malicious torrent download. Once in the computer, it encrypts all personal files stored on it and marks each of them with additional .irfk extension. Furthermore, it leaves _readme.txt ransom note in every scanned folder. The virus then deletes Volume Shadow Copies to block access to System Restore points. Additionally, the virus modifies Windows HOSTS file by adding a list of websites to block on the host, thus restricting victim’s access to various computer help sites. This ransomware often infects computers with information stealers such as AZORULT Trojan or VIDAR.
Ransom note	_readme.txt
Ransom demand	$490-$980 in Bitcoin
Distribution	Victims often download this ransomware along illegal torrent downloads, cracked software, activators, key generators or tools like KMSPico.
Known software cracks to contain this malware	Corel Draw, Tenorshare 4ukey, Adobe Photoshop, Cubase, Adobe Illustrator, Internet Download Manager, Tally, League of Legends.
Detection names	Trojan:Win32/Krypter.AA!MTB (Microsoft), Gen:Variant.Fragtor.36858 (B) (Emsisoft), UDS:Trojan.Win32.Scarsi.gen (Kaspersky), Gen:Variant.Fragtor.36858 (BitDefender), MachineLearning/Anomalous.95% (Malwarebytes), Packed.Generic.528 (Symantec) see all detection name variations on VirusTotal
Removal	Remove ransomware and related malware from your PC using professional software of your choice. We highly recommend using INTEGO Antivirus. To repair virus damage on Windows OS files, consider scanning with RESTORO.

REMOVE MALWARE & REPAIR VIRUS DAMAGE

Viruses under the ransomware type use stealthy techniques to infect computers

Ransomware-type viruses can infect your computer in a variety of ways. Most common distribution methods rely on torrent files, fake ads, exploit kits, malicious email attachments or simply deceptive websites serving various downloads. When it comes to STOP/DJVU ransomware variants like IRFK virus or others, we can confirm that the main attack vector is illegal torrents for popular software cracks. Many victims who got their files encrypted state that the ransomware came along a torrent for pirated software version. Some examples of programs that users attempted to download and activate without paying the license fee are:

• AutoCad;
• Accurate 5;
• Adobe Photoshop;
• Adobe Illustrator;
• Opera browser;
• Fifa 20;
• Tenorshare 4ukey;
• Microsoft Office 365;
• CorelDraw;
• VMware Workstation;
• Cubase;
• phpStorm;
• League of Legends;
• Internet Download Manager;
• KMSPico (illegal Windows activation tool).

Please remember that this list is not finite and you can get infected with this malware after downloading any crack or keygen for popular programs and games for Windows PCs. Cybercriminals know which programs are popular and use their names to prey on potential victims by uploading torrents for such software in various online listings. Therefore, if you have bad habits of downloading pirated software versions, you risk falling a victim to a ransomware attack.

Our suggestion is to support legitimate software developers and download computer programs only from verified websites only. Trying to avoid license fees can only do a lot of harm to your data – either files saved on your computer or login credentials. These torrents hardly ever come clean as they tend to carry all sorts of malware – viruses, Trojans, keyloggers, cryptocurrency miners and so on. It is worth noting that software license tends to cost less than hefty ransoms asked by cybercriminals.

Another ransomware distribution technique often used by offenders is malspam. The attackers tend to compose convincing email messages along with attached files that carry the infection inside of them. These attachments are typically named as common documents used in daily work or personal communications – invoices, order summaries, waybills, pending payment and similar. The contents of such emails often urge the target to open the attached file or link as soon as possible and reply to the sender. The offenders may pretend to be someone else, for instance, colleague from your work, boss, or a legitimate company representative. The attachments typically come in Word, Excel or PDF document formats and carry a malicious code based on JavaScript or Macros. Once opened, the script downloads and runs the malware on your computer.

It gets harder and harder to identify malicious emails nowadays since attackers try to make them look as convincing as possible. They may insert logos, spoof the sender’s email address or try to spark your curiosity by stating that there’s information that you need to review as soon as possible. We advice you to learn how to identify spoofed sender’s email address and avoid opening emails that you didn’t wait for or if you have even a slight suspicion that something’s wrong with the email.

You can also get infected by visiting dangerous online websites or clicking on malicious ad. Cybercriminals often use malvertising, a technique that is used to inject malicious code into legitimate ad networks to infect many users at once. Clicking on such ads or even worse, downloading files promoted by them can compromise your operating system in seconds. The best way to protect your PC against such attacks is to have a robust antivirus with real-time protection feature on your computer.

STOP/DJVU ransomware victims should also know that without a backup, there are no magic tools that can help to decrypt your files. The only exceptions are described in this article on decrypting/repairing files affected by STOP/DJVU variants. Please note that attempts to desperately search for a non-existent decryption tool can result in double file encryption. There are other ransomware strains that target potential victims with fake decryption tools. If you happen to download and run one on your computer, your files will get encrypted again. One example of virus using this distribution technique is ZORAB.

Details about the ransomware infection: what really happened?

It is understandable that you feel unsettled because it is unclear what really happened and what the IRFK ransomware virus did to your computer. In this section, we will go through technical details and overview the modus operandi of this threat.

After being launched on the target system, the ransomware unwraps its processes that may be named as build.exe, build2.exe, build3.exe and similar. Before actually encrypting one’s files, the virus performs a couple of initial checks, for instance, if the victim’s computer’s geolocation is eligible for data encryption. The virus connects to https[:]//api.2ip.ua/geo.json and as a response, geo.json file is saved to the computer. This file contains information such as computer’s IP address, time zone, country code, zip code, latitude and longitude.

The virus then compares the retrieved country code with its exception list, and stops the attack if one of the following countries is detected: Russian Federation, Belarus, Armenia, Tajikistan, Kazachstan, Kyrgyzstan, Ukraine, Uzbekistan or Syria. The reason why the virus avoids infecting victims from these countries are unknown, although it can be explained that users from these countries hardly ever pay ransoms or that the cybercriminals are based in this region themselves.

If the infected computer is based in other country, the virus also runs commands to gather details about the infected system. It saves hardware and software related details in information.txt file. A screenshot of such file contents is shown down below.

Before starting the file encryption process, the ransomware tries to connect to its Command&Control server and get unique encryption key (also known as online key) for the victim along with Personal ID string. The virus then saves these details to bowsakkdestx.txt and PersonalID.txt files. In case the server is unreachable or there are problems with victim’s Internet connection, the virus uses a hardcoded encryption key instead (also known as the offline key). At this point, it is worth mentioning that there are no hopes to decrypt files affected with online key, whereas offline key encryption leaves some chances to recover your data. You can spot offline encryption type by checking the last two characters in your ID in PersonalID.txt file located in C:/SystemID. If these are t1, it means that offline key was used.

The ransomware then runs a fake Windows update prompt called winupdate.exe which shows a progess bar for the victim. This is done in order to convince the computer user that the system slowdown is caused by ongoing legitimate operating system updates. In the meantime, the ransomware uses Salsa20 encryption to lock files and secures this encryption with RSA-2048 public key. To make affected files distinguishable, the malware appends .irfk extensions to original full filenames and drops _readme.txt notes in each data folder.

Below, you can see a screenshot of _readme.txt file used in the latest STOP/DJVU ransomware attacks.

The next step taken by ransomware operators is ensuring that the victim can no longer use System Restore points to recover some of the files. Therefore, the virus deletes Volume Shadow Copies by entering the following command in Command Prompt:

^{vssadmin.exe Delete Shadows /All /Quiet}

You may also notice that you can no longer reach specific websites online. The reason behind this is that the criminals do not want you to find relevant information or help online, therefore they’ve designed the ransomware to add a list of domain names to Windows HOSTS file and map them to localhost IP. This causes DNS resolution problem and causes DNS_PROBE_FINISHED_NXDOMAIN error to appear in web browsers.

In the end, to cause even more damage, the ransomware drops information stealer on the system, either AZORULT or VIDAR Trojan. These threats can be used to access victim’s computer via command line and run commands to steal login credentials for software or web browser-saved accounts, banking details, Skype chat history, cryptocurrency wallets and more. The criminals might use such information for further blackmail.

Remove IRFK Ransomware Virus and Recover Your Files

The most important task after being with such notorious ransomware is to remove it from your computer system. We recommend using an up-to-date antivirus that can automatically detect all malicious files and safely delete them for you. This must be done after booting the computer in Safe Mode with Networking. If you do not have AV software yet, consider using INTEGO Antivirus to remove IRFK ransomware virus. This AV is approved by our team, has excellent malware detection rate and provides real-time monitoring to block attempts to infect your computer. Additionally, we advise downloading RESTORO to repair damage caused for Windows OS files.

If you have already completed IRFK virus removal, now it is time to restore your files from a backup. If you do not have it, follow these guidelines on how to decrypt/repair files locked by STOP/DJVU variants. Additionally, we suggest reporting cybercrime incident to your local law enforcement agencies and changing passwords for all browser-saved accounts as well as for profiles for software installed on your computer.

OUR GEEKS RECOMMEND

Our team recommends a two-step rescue plan to remove ransomware and other remaining malware from your computer, plus repair caused virus damage to the system:

GeeksAdvice.com editors select recommended products based on their effectiveness. We may earn a commission from affiliate links, at no additional cost to you. Learn more.