Antivirus software from Avast blocked more than 34 million attempts to use computers for cryptomining last Sunday, the 3rd of December. Never before the antivirus vendor blocked so many attempts to abuse computers for cryptomining on a single day.
Interestingly, all detections took place in Google's Chrome browser, according to Avast security researcher Denis Konopiský. Avast suspects that the Javascript code that is used to mine the Monero crypto currency was injected into a Chrome extension, but the antivirus vendor is not entirely sure yet.
"Either this is a malicious campaign that was effectively spread, or a popular extension was modified to include the miner," Konopiský writes.
All attempts concerned Javascript code, that is Avast has called 'JS:Miner-I'. The script uses the cryptonight algorithm to mine Monero, an anonymous cryptocurrency. For the mining cryptographic calculations have to be performed that are CPU intensive.
In most cases this happens without the user noticing anything. However some users find out because the computer becomes slower because the mining script heavily utilizes the CPU.
