Nice piece of research:
Abstract: Among the many types of malicious codes, ransomware poses a major threat. Ransomware encrypts data and demands a ransom in exchange for decryption. As data recovery is impossible if the encryption key is not obtained, some companies suffer from considerable damage, such as the payment of huge amounts of money or the loss of important data. In this paper, we analyzed Hive ransomware, which appeared in June 2021. Hive ransomware has caused immense harm, leading the FBI to issue an alert about it. To minimize the damage caused by Hive Ransomware and to help victims recover their files, we analyzed Hive Ransomware and studied recovery methods. By analyzing the encryption process of Hive ransomware, we confirmed that vulnerabilities exist by using their own encryption algorithm. We have recovered the master key for generating the file encryption key partially, to enable the decryption of data encrypted by Hive ransomware. We recovered 95% of the master key without the attacker’s RSA private key and decrypted the actual infected data. To the best of our knowledge, this is the first successful attempt at decrypting Hive ransomware. It is expected that our method can be used to reduce the damage caused by Hive ransomware.
Here’s the flaw:
The cryptographic vulnerability identified by the researchers concerns the mechanism by which the master keys are generated and stored, with the ransomware strain only encrypting select portions of the file as opposed to the entire contents using two keystreams derived from the master key.
The encryption keystream, which is created from an XOR operation of the two keystreams, is then XORed with the data in alternate blocks to generate the encrypted file. But this technique also makes it possible to guess the keystreams and restore the master key, in turn enabling the decode of encrypted files sans the attacker’s private key.
The researchers said that they were able to weaponize the flaw to devise a method to reliably recover more than 95% of the keys employed during encryption.
More Stories
Live Video of Promachoteuthis Squid
The first live video of the Promachoteuthis squid, filmed at a newly discovered seamount off the coast of Chile. Blog...
YubiKey Side-Channel Attack
There is a side-channel attack against YubiKey access tokens that allows someone to clone a device. It’s a complicated attack,...
Spyware Vendors’ Nebulous Ecosystem Helps Them Evade Sanctions
The secret web of at least 435 entities across 42 countries making up the spyware landscape facilitates unpunished security and...
US and Allies Accuse Russian Military of Destructive Cyber-Attacks
The joint government advisory highlighted the cyber activities of Unit 29155, which has launched destructive cyber-attacks against critical infrastructure globally...
PyPI Revival Hijack Puts Thousands of Applications at Risk
Revival Hijack Python Package Index supply chain attack threatens 22,000 packages through malicious downloads Read More
Security Budgets Come Under Pressure as “Hypergrowth” Ends
Despite rising threats researchers find a third of firms see flat or falling security budgets and hiring slows Read More