Unofficial activation ('cracking') tools are illegal programs that supposedly activate licensed software free of charge and bypass activation, however, they often install other malicious programs instead. Note that malware can only be distributed in this way if Trojans are already installed on computers. Trojans are malicious programs that can cause chain infections by installing other software of this kind. When users download and open (execute) the files, however, they inadvertently install malware.įake software updating tools cause damage by installing malware rather than updates/fixes for installed software, or by exploiting bugs/flaws of outdated software. These are used to distribute malicious files by disguising them as legitimate and regular. If the documents are opened with MS Office versions prior to 2010, however, the documents install malicious software automatically, since these older versions do not include "Protected View" mode.Įxamples of untrusted file and software download sources are Peer-to-Peer networks (torrent clients), free file hosting websites, freeware download sites, and unofficial web pages. Note that malicious MS Office documents can install malware only when users enable editing/content (macros commands). Cyber criminals usually attach a Microsoft Office document, archive file (ZIP, RAR), PDF document, executable file (.exe) or JavaScript file, and wait until recipients open it. Their main goal is to trick recipients into executing the file, which then infects the computer with malware. Using malspam, criminals send emails that have a malicious file attached, or include a website link designed to download a malicious file. Ransomware and other malware infections are commonly spread through malspam campaigns, untrusted file/software download sources, fake (third party) software updating tools, Trojans and unofficial software activation tools. More ransomware examples are Lockerxxs, 16x and Covid-20. Victims usually cannot decrypt their files with free software and, therefore, you should have files backed up on a remote server such as Cloud and/or unplugged storage device. Typically, these backups are the only free data recovery option. Main differences are usually size of ransom and encryption algorithm ( symmetric or asymmetric) that ransomware uses for data encryption. Typically, ransomware generates ransom messages that contain instructions about how to contact cyber criminals for payment information and other details. In summary, ransomware is malware that encrypts files and keeps them inaccessible unless they are decrypted with tools held only by the developers. Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data: Therefore, ransomware victims are advised not to pay any ransoms and choose another data recovery option - restore files from a backup if possible.įurther encryption of any unaffected files can be prevented by uninstalling the ransomware, however, already compromised files remain encrypted even after removal of the rogue software. Note that paying the ransom does not guarantee that ransomware developers will send any decryption tools. Unfortunately, there are no third party tools that can decrypt files that are encrypted by Coos ransomware - only cyber criminals behind this ransomware hold valid decryption tools. Victims are informed that decryption tools can be purchased for USD$980 or $490, depending on whether victims send a message to or within 72 hours of the attack. The ransom message ("_readme.txt" file) states that the only way for victims to decrypt their files is to use decryption software and a unique key that can be purchased from developers of Coos ransomware. coos" extension to filenames. For example, " 1.jpg" is renamed to " 1.jpg.coos", " 2.jpg" to " 2.jpg.coos", and so on. It encrypts and renames victims' files, and creates the " _readme.txt" file (a ransom message) in all folders that contain encrypted files.Ĭoos renames each encrypted file by appending the ". Coos is ransomware belonging to the Djvu family.
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