Virus Information
A computer virus is a type of computer program that can replicate itself on your computer and spread to other devices.
You might be infected with a virus if your computer suddenly starts running more slowly, crashes a lot, or does things like running unusual programs without your permission. Here's a few things you need to know about viruses, including some major types, signs you're infected, and how to avoid them. In more technical terms, a computer virus is a type of malicious code or program written to alter the way a computer operates and is designed to spread from your PC to another. A virus operates by inserting or attaching itself to a legitimate program for example email or even a file or document that supports macros in order to execute its code.
Malware Information
These days, the term malware refers to a large variety of software which all has one thing in common: it is unwanted software which someone else wants to run on your computer. This software infects your computer, making it behave in a way which you have not approved of. Malware can sometimes include traditional viruses and worms, which are usually destructive in some way - these can delete files, wreck the operating system and change the behaviour of your computer. Spyware has often been referred to as a virus, but this is not wholly accurate. Often the software does not duplicate itself like a virus, which is why it is almost never detected when a simple anti-virus program like the commonly used McAfee, Norton, Kaspersky, AVG, AVAST, ESET, Panda, FSecure and Bitdefender anti virus scans are run. Some modern trojan viruses and worms can give control of your computer to an attacker. Once hacked in they can then use your computer to send spam emails of themselves to all of the people in your address book or launch attacks on other computers. One of the newest types of Viral infection has been dubbed ransomware and can literally hold your personal data to ransom.
Ransomware
A common type of Ransomware is CryptoLocker this trojan targeted computers running Windows Operating Systems although more recently ransomware has been found on Mac OS X. it it is believed to have first been posted to the Internet in late 2013. CryptoLocker propagated via infected email attachments, often claiming missed parcel deliveries etc. When activated, the ransomware encrypts certain types of files stored on local and mounted network drives (including all types of office documents emails pictures websites and accounting files etc) using RSA public-key cryptography, with the private key stored only on the malware's control servers. The malware then displays a message which offers to decrypt the data if a payment (through either Bitcoin or a pre-paid cash voucher) is made by a stated deadline, and threatened to delete the private key if the deadline passes. If the deadline is not met, the malware offered to decrypt data via an online service provided by the malware's operators, for a significantly higher price in Bitcoin.
Although CryptoLocker itself is easily removed with anti-malware tools, the affected files remained encrypted in a way which some virus researchers considered infeasible to break. Many said that the ransom should not be paid, but did not offer any other way to recover the encrypted files; others said that paying the ransom was the only way to recover files that had not been backed up. Most victims claimed that paying the ransom did not lead to the files being decrypted in any case, and on top of the deleted data now lost a significant sum of money. The virus has changed significantly in the last seven years and although some reports from 2020 say that certain files can now be decrypted from the FireEye, virtually all newer variants of the virus cannot.
Some of the above information is updated from a cryptolocker Wikipedia article.