A Method for Decrypting Data Infected with Rhysida Ransomware

Fuente: arXiv
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Main Authors: Kim, Giyoon, Kang, Soojin, Baek, Seungjun, Kim, Kimoon, Kim, Jongsung
Format: Preprint
Published: 2024
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author Kim, Giyoon
Kang, Soojin
Baek, Seungjun
Kim, Kimoon
Kim, Jongsung
author_facet Kim, Giyoon
Kang, Soojin
Baek, Seungjun
Kim, Kimoon
Kim, Jongsung
contents Ransomware is malicious software that is a prominent global cybersecurity threat. Typically, ransomware encrypts data on a system, rendering the victim unable to decrypt it without the attacker's private key. Subsequently, victims often pay a substantial ransom to recover their data, yet some may still incur damage or loss. This study examines Rhysida ransomware, which caused significant damage in the second half of 2023, and proposes a decryption method. Rhysida ransomware employed a secure random number generator to generate the encryption key and subsequently encrypt the data. However, an implementation vulnerability existed that enabled us to regenerate the internal state of the random number generator at the time of infection. We successfully decrypted the data using the regenerated random number generator. To the best of our knowledge, this is the first successful decryption of Rhysida ransomware. We aspire for our work to contribute to mitigating the damage inflicted by the Rhysida ransomware.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06440
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Method for Decrypting Data Infected with Rhysida Ransomware
Kim, Giyoon
Kang, Soojin
Baek, Seungjun
Kim, Kimoon
Kim, Jongsung
Cryptography and Security
Ransomware is malicious software that is a prominent global cybersecurity threat. Typically, ransomware encrypts data on a system, rendering the victim unable to decrypt it without the attacker's private key. Subsequently, victims often pay a substantial ransom to recover their data, yet some may still incur damage or loss. This study examines Rhysida ransomware, which caused significant damage in the second half of 2023, and proposes a decryption method. Rhysida ransomware employed a secure random number generator to generate the encryption key and subsequently encrypt the data. However, an implementation vulnerability existed that enabled us to regenerate the internal state of the random number generator at the time of infection. We successfully decrypted the data using the regenerated random number generator. To the best of our knowledge, this is the first successful decryption of Rhysida ransomware. We aspire for our work to contribute to mitigating the damage inflicted by the Rhysida ransomware.
title A Method for Decrypting Data Infected with Rhysida Ransomware
topic Cryptography and Security
url https://arxiv.org/abs/2402.06440