Every detection engine has the same weakness: it can only catch what it knows about at the moment of scanning. A file that is clean by today's signatures but malicious by tomorrow's gets a free pass. Retrospective scanning attacks that gap directly — it goes back and re-checks delivered content against updated intelligence.

Votiro Cybersec Ltd.'s US10664602B2, “Determining malware prevention based on retrospective content scan” (issued May 26, 2020; CPC G06F 21/56 family — malware detection, and H04L 63/145 — malicious-traffic protection), describes basing the prevention decision on a scan performed after the fact, not only at the gateway. Read it at US10664602B2.

“The disclosed embodiments include a method for retroactively analyzing original input content to detect malicious content in a computer system, in which the original input content has been previously processed to generate modified input content and prevented from being received by an intended recipi…”— U.S. Patent No. 10,664,602 source

Mechanically, this means the system keeps enough context about delivered files to re-evaluate them when the threat picture changes — and to act (quarantine, alert, remediate) on a verdict that flips from clean to malicious. It is the security equivalent of a recall notice: the product was shipped, then later found defective, and the system can reach back to it.

Why this is a business story: content disarm and reconstruction, plus retrospective scanning, became the basis for a category of email and file-security vendors selling “zero-trust to the file” as a recurring service. The commercial logic is the same as MDR: the value is in the continuous re-evaluation, which only works as a subscription, not a one-time scan.

The grounded read: retrospective scanning accepts that day-zero detection will miss things and builds the ability to catch them after delivery. Votiro's 2020 grant frames malware prevention as a decision that can be made retrospectively, not only at the moment of entry.