New malware steals bitcoin using a technique that modifies an infected machine’s clipboard content.

In July 2018, Fortiguard Labs reported on a new malicious campaign, Bitcoin Stealer, which is currently responsible for taking approximately $60,000 in bitcoin. FortiGuard Labs researchers first came across a threat that initially matched several rules specific to Jigsaw ransomware in April 2018.

However, a closer look revealed that the threat, which contained the assembly name “BitcoinStealer.exe,” didn’t behave like ransomware at all.

How Clipboard Hijacking Tricks Users

Bitcoin Stealer instead uses an executable to monitor an infected computer’s clipboard content for signs of a bitcoin address. Assuming it finds one, Bitcoin Stealer replaces the copied bitcoin address with one that has similar strings at the beginning and end of its wallet address. Using this technique, Bitcoin Stealer injects itself into bitcoin transactions and tricks users into sending cryptocurrency to a wallet controlled by the cyberattacker behind the malware.

Bitcoin Stealer is the latest threat capable of monitoring and changing clipboard content — but it’s not the first. The malware comes on the heels of Evrial, which hit in January 2018, according to Bleeping Computer. It also follows CryptoShuffler, which redirected $150,000 in the fall of 2017.

These thieving programs are examples of clipboard hijacking, an attack methodology through which attackers commonly change clipboard content to direct browser users to a malicious website, according to Techopedia. Bad actors are also known to use a tactic called “pastejacking” to interfere with commands copied from a web browser and pasted into the terminal.

How Can Security Professionals Protect Against Clipboard-Modification Attacks?

Digital attackers have a long history of targeting clipboards to steal cryptocurrency or redirect users to malware. Therefore, security professionals must take steps to protect organizations against these types of clipboard-modification attacks.

Aside from searching for and blocking known indicators of compromise (IOCs) for threats like Bitcoin Stealer, IBM Security experts recommend installing updated antivirus software on all workstations. They also stress the importance of security awareness training, which teaches users to cross-reference sender and recipient addresses (among other things), and the integration of machine learning into virus protection defenses.

Sources: Fortinet, Techopedia, Bleeping Computer