Back in 2019 client asked me to build an anti-virus feature in Azure to identify and eliminate any malware potentially uploaded by end-users. Back then we delivered this feature using ClamAV open-source antivirus software running in VM. In 2023, after Microsoft Defender for Storage became generally available in our target region, we compared it with ClamAV and decided to switch.

Now 1 year passed since we switched to Defender and it is time to compare both approaches and share experience and lessons learned from building, supporting and operating both approaches.