Viruses

SethLocker is a recently-discovered ransomware infection. Cybercriminals use it to run encryption of potentially important files and then urge victims into paying money for their decryption. As opposed to many other similar infections that add their own extension to the end of filenames, SethLocker does run any visual alterations and leaves all files and icons in their original look. Despite this, the data is nonetheless encrypted and victims are prevented from accessing it. To return the blocked data, threat actors have written instructions in a text note called HOW_DECRYPT_FILES.txt. It says all essential files have been encrypted due to a vulnerability within the system. In order to redo the malicious changes, victims are obliged to contact the swindlers via one of their e-mail addresses and pay money for decryption. The price for decryption is not disclosed in the message, however, cybercriminals claim it to be "too small". In addition, victims are also allowed to send one non-valuable file and get it decrypted for free. This way cyber-crooks show their ability to decrypt the files and additionally give extra motivation for paying the ransom. Note that paying the ransom is usually not recommended since some extortionists fool their victims and do not send any decryption tools after the payment.

DVN is a ransomware infection that runs strong encryption to hostage potentially important files until a ransom is paid. In addition to encryption, the virus also assigns the .devinn extension to highlight the blocked data; changes the desktop wallpapers; and create the unlock_here.txt text note with recovery instructions. Cybercriminals say they will provide the necessary decryption software only if victims pay 0.0077 BTC (around $200). It is stated the payment can be done only in Bitcoin and to the attached crypto address. Unlike many other ransomware infections, developers behind DVN Ransomware do not include any means of communication with them (e.g., e-mail, various messengers, etc.). Thus, it is very unclear how victims will communicate with the attackers in order to receive the promised decryption tool after making the payment. Paying the ransom is highly not recommended since there is a risk of not getting anything in return. Unfortunately, we have to note that cybercriminals are usually the only figures actually capable of fully decrypting access to data.

Fofd Ransomware (version of STOP Ransomware or DjVu Ransomware) is a high-risk widespread encryption virus, that first appeared near 5 year ago. It experienced several visual and technical changes throughout the time. In this tutorial, we will analyze recent versions of this dangerous malware. In the very end of April 2023, STOP Ransomware started to add following extensions to encrypted files: .fofd. It is because of that, it got the name "Fofd Ransomware" although it is just one of the varieties of STOP crypto-virus. The virus also modifies "hosts" file to block Windows updates, antivirus programs, and sites related to security news or offering security solutions. The process of infection also looks like installing Windows updates, malware shows the fake window, that imitates the update process. A new subtype of STOP Ransomware uses same e-mail addresses, as few previous generations: support@freshmail.top and datarestorehelp@airmail.cc. Fofd Ransomware creates _readme.txt ransom note file.

WannaCry (also referred to as Wcry, Wana Decrypt0r 2.0, WanaDecryptor, and WNCRY virus) is a ransomware infection that encrypts personal files using AES-128 algorithms and demands victims to pay for decryption. The virus was discovered by a security researcher S!Ri and there are a couple of known WannaCry variants. Depending on which variant attacked the system, files affected by encryption will be altered using the .wcry, .wncry, or WNCRYT (for encrypted .bmp files). For instance, a file like 1.pdf will change to 1.pdf.wcry or similarly depending on the ransomware version. Following this, the virus displays decryption instructions in a force-opened pop-up window. One of the variants changes the desktop wallpapers as well. The Wana Decrypt0r 2.0 variant also creates a separate ransom-demanding note called @Please_Read_Me@.txt.

If your files recently got .foty extensions, that means your PC is infected with an encryption virus called Foty Ransomware (part of STOP Ransomware or Djvu Ransomware family, called so because the first versions of the virus of this type appended .djvu extension). This is a very widespread and actively distributed malware. Ransomware initially used the AES-256 encryption algorithm, and there was no way for decryption. However, if during the encryption process the infected PC was out of the internet, or connection with a remote server of hackers was interrupted your files can be decrypted, using methods provided below. STOP Ransomware has a ransom note called _readme.txt. In this text file, malefactors give contact information and details on how to make a payment. The virus copies it on the desktop and in the folders with encrypted files. Hackers provide following contacts, e-mails: support@freshmail.top and datarestorehelp@airmail.cc.

Foza Ransomware is a devastating encryption virus from the series of STOP Ransomware (Djvu Ransomware). Foza Ransomware is a variant of the STOP/Djvu Ransomware family, which is known for using a combination of two encryption algorithms: RSA and AES. RSA is used to encrypt the symmetric AES key that is generated for each file. This means that each file has its own unique AES key, which is used to encrypt and decrypt the file's contents. The RSA key pair is generated by the ransomware on the victim's computer and the public key is sent to the attacker's server, which is then used to encrypt the symmetric AES key. It has got its name from .foza extension, that ransomware adds to the end of encrypted files. From a technical point of view, the virus remains the same as previous versions. Only thing that changes during past couple of years is contact details of malefactors.

Kafan is a new ransomware virus that infects Windows users in order to encrypt personal data and extort money for its decryption from victims. Once installed, the ransomware will run a quick scan of the stored data and start the encryption process using strong cryptographic algorithms. In addition, the malware will also assign its own .kafan extension to distinguish locked files. For instance, a file originally named 1.pdf will change to 1.pdf.kafan and become no longer accessible. Lastly, the file encryptor generates a ransom note called help_you.txt with instructions on how to return the data. The ransom message necessitates victims to send an e-mail message to cybercriminals (PYTHONHAVENONAME@163.COM) and pay for decryption. While sending the message, victims are also asked to write their ID in the message title/subject. The price for decryption is said to depend on how fast victims establish communication with the attackers. Cybercriminals employ such manipulation techniques to put extra pressure on victims and potentially force them into agreeing to pay the ransom.

Recov is a new ransomware variant of the VoidCrypt family. After infiltrating a system, it runs data encryption (to prevent victims from accessing files) and tells victims to pay for a kit of decryption software + RSA key for unlocking the files. Instructions on how to do it are presented inside the Dectryption-guide.txt ransom note. One more thing that this ransomware does is assigning visual changes to encrypted files - a string of characters consisting of the victim's ID, cybercriminals' e-mail address, and the .Recov extension will be added to filenames. For instance, a file originally named 1.pdf will be changed to 1.pdf.[MJ-TN2069418375](Recoverifiles@gmail.com).Recov or similarly. Cybercriminals demand that victims establish contact with them via e-mail (Recoverifiles@gmail.com or Recoverifiles@protonmail.com in case of no answer). While it isn't made clear what extortionists need, it is likely that they will require their victims to pay a certain fee for a decryption tool and RSA key that are available only to the developers.