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Analysis Shows How Fast Various Ransomware Strains Encrypt 100,000 Files

Cybersecurity researchers at Splunk have conducted an analysis to determine how long it takes various ransomware strains to encrypt files on compromised systems.

The analysis focused on ten major ransomware families and the goal was to encrypt nearly 100,000 files with a total size of approximately 54 Gb. The files were stored on four hosts — two running Windows 10 and two running Windows Server 2019. In addition to encryption speed and duration, the researchers also looked at how the ransomware used system resources.

They measured the encryption time for Avaddon, Babuk, BlackMatter, Conti, DarkSide, LockBit, Maze, Mespinoza (PYSA), REvil and Ryuk, with 10 samples analyzed for each malware family.

The researchers measured the time it took each sample to encrypt the 100,000 files and they used the median value to show the speed of each family.

The results showed that LockBit was the fastest with 5 minutes and 50 seconds, followed by Babuk at 6 minutes 34 seconds. The notorious Conti encrypted the files in just under one hour, with Maze and Mespinoza being the slowest, at nearly two hours. The average across all strains was 43 minutes.

Ransomware encryption time

“The average median duration demonstrates a limited window of time to respond to a ransomware attack once the encryption process is underway,” Splunk researchers noted. “This can prove even more limiting considering that the catastrophic apex may be when a single critical file is encrypted, rather than the whole of the victim’s data. With such factors in play, it may prove to be extremely difficult, if not impossible, for the majority of organizations to mitigate a ransomware attack once the encryption process begins.”

The analysis also showed that only some ransomware takes advantage of better hardware to speed up the encryption process. The amount of memory that a device has does not appear to have a significant influence, and storage disk speeds may lead to faster encryption, but this is most likely if the malware can also take full advantage of a CPU’s capabilities.

“We observed that some families utilized increased system resources better than others,” the researchers said in their report. “Some of the families were very efficient, while others tended to utilize large percentages of CPU time along with very high disk access rates. There was no direct correlation between a sample using a larger amount of system resources with a faster encryption speed. Some ransomware families performed worse, or even crashed, when deployed on the faster test systems.”

Related: Researchers Devise Method to Decrypt Hive Ransomware-Encrypted Data

Related: University Project Cataloged 1,100 Ransomware Attacks on Critical Infrastructure

Related: Mamba Ransomware Leverages DiskCryptor for Encryption, FBI Warns

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.