Yes - any attachments added to Greenhouse Recruiting are scanned to ensure security issues won't disrupt your hiring process.
In most cases, you'll never see the virus scanner, but it will run in the background when a new document is uploaded. Additionally, any questionable attachments are removed from automated candidate emails, such as a new candidate applying to a job.
If Greenhouse Recruiting detects an issue, you'll be notified and asked to confirm before downloading the file.
Additionally, Greenhouse Recruiting will warn you about any malicious files if you try to email your recruiting team about a candidate so you don't inadvertently impact other users in your organization.