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Cryptography Module Detection and Identification Mechanism on Malicious Ransomware Software

악성 랜섬웨어 SW에 사용된 암호화 모듈에 대한 탐지 및 식별 메커니즘

  • Hyung-Woo Lee (Division of Computer Engineering, Hanshin University)
  • 이형우 (한신대학교 컴퓨터공학부)
  • Received : 2022.10.28
  • Accepted : 2022.12.08
  • Published : 2023.02.28

Abstract

Cases in which personal terminals or servers are infected by ransomware are rapidly increasing. Ransomware uses a self-developed encryption module or combines existing symmetric key/public key encryption modules to illegally encrypt files stored in the victim system using a key known only to the attacker. Therefore, in order to decrypt it, it is necessary to know the value of the key used, and since the process of finding the decryption key takes a lot of time, financial costs are eventually paid. At this time, most of the ransomware malware is included in a hidden form in binary files, so when the program is executed, the user is infected with the malicious code without even knowing it. Therefore, in order to respond to ransomware attacks in the form of binary files, it is necessary to identify the encryption module used. Therefore, in this study, we developed a mechanism that can detect and identify by reverse analyzing the encryption module applied to the malicious code hidden in the binary file.

랜섬웨어에 의해 개인용 단말 또는 서버 등이 감염되는 사례가 급증하고 있다. 랜섬웨어는 자체 개발한 암호화 모듈을 이용하거나 기존의 대칭키/공개 키 암호화 모듈을 결합하여 공격자만이 알고 있는 키를 이용하여 피해 시스템 내에 저장된 파일을 불법적으로 암호화 하게 된다. 따라서 이를 복호화 하기 위해서는 사용된 키 값을 알아야만 하며, 복호화 키를 찾는 과정에 많은 시간이 걸리므로 결국 금전적인 비용을 지불하게 된다. 이때 랜섬웨어 악성코드는 대부분 바이너리 파일 내에 은닉된 형태로 포함되어 있어 프로그램 실행시 사용자도 모르게 악성코드에 감염된다. 그러므로 바이너리 파일 형태의 랜섬웨어 공격에 대응하기 위해서는 사용된 암호화 모듈에 대한 식별 과정이 필요하다. 이에 본 연구에서는 바이너리 파일 내 은닉된 악성코드에 적용 된 암호화 모듈을 역분석하여 탐지하고 식별할 수 있는 메커니즘을 연구하였다.

Keywords

Acknowledgement

이 성과의 일부는 2022년도 정부(과학기술정보통신부)의 재원으로 한국연구재단의 지원을 받아 수행된 연구임 (No 2021R1F1A1046954).

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