How Can an Algorithm Stop Ransomware in Real Time?

Ransomware is the malware that encrypts your files and demands a ransom. A recent study examined 97 real cases and found that almost all (95.88 %) try to encrypt data. To fight it, the authors created Simple Format Analysis (SFA), a method that checks file formats in three versions: SFA‑F, which looks at fixed structure; SFA‑H, which reads header information; and SFA‑F‑H, a hybrid that combines both. These algorithms can spot an attack with an accuracy between 95 % and 97.9 %, outperforming existing solutions. The real breakthrough is “real‑time recovery”: while the file is being written, the system monitors input and output and, if encryption is detected, launches an immediate restoration process. In practice, the file never gets damaged. This approach could drastically cut ransomware damage, especially in companies where document loss is critical. While it doesn’t erase the threat entirely, it adds an active, fast defense layer, making it harder for hackers to get their loot.

Simple Format Analysis (SFA) relies on two core principles of file structure: the presence of a fixed layout (as in PDF sections) and header information that describes the file type. In the SFA‑F variant, the algorithm compares fixed‑position bytes with known patterns, spotting anomalies typical of encryption, such as the replacement of signature sequences with random values. SFA‑H, on the other hand, examines the first kilobytes of the file where metadata resides; encryption often corrupts these headers, making the file unrecognizable by the operating system. The hybrid SFA‑F‑H leverages both analyses, enhancing robustness against ransomware that tries to mask modifications. For real‑time recovery, the system inserts an I/O "watchdog": every write operation is intercepted, and if the data stream shows an entropy increase (a hallmark of encryption) above a predefined threshold, the watchdog triggers a temporary backup copy. This copy is then compared with the original version, and if needed, the file is reconstructed using the still‑unencrypted blocks. The approach demands efficient memory management to avoid bottlenecks, but tests show the introduced latency is negligible compared to typical ransomware encryption times. Moreover, integration with existing monitoring systems (like SELinux or Windows Defender) enables easy adoption in enterprise environments, lowering implementation costs. Future work aims to extend SFA to emerging file formats and incorporate machine‑learning techniques to fine‑tune entropy thresholds based on the specific behavior of new ransomware strains.