Vidar Stealer is a type of information stealing malware that targets personal and sensitive information such as login credentials, credit card details, and cryptocurrency wallets. It infects a user's system through phishing emails or malicious downloads, and then gathers data by logging keystrokes or taking screenshots. The stolen information is then sent to the attacker's remote server. Vidar Stealer is highly customisable and can be purchased on dark web marketplaces, making it a popular choice for cybercriminals. Users can protect themselves by using up-to-date antivirus software and being cautious when opening emails or downloading files from unknown sources.