Identifying Evasive Code in Malicious Websites by Analyzing Redirection Differences

Yuta TAKATA  Mitsuaki AKIYAMA  Takeshi YAGI  Takeo HARIU  Kazuhiko OHKUBO  Shigeki GOTO  

IEICE TRANSACTIONS on Information and Systems   Vol.E101-D    No.11    pp.2600-2611
Publication Date: 2018/11/01
Publicized: 2018/08/22
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2017ICP0005
Type of Manuscript: Special Section PAPER (Special Section on Information and Communication System Security)
Category: Mobile Application and Web Security
malicious website,  redirection,  javascript,  evasive code,  

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Security researchers/vendors detect malicious websites based on several website features extracted by honeyclient analysis. However, web-based attacks continue to be more sophisticated along with the development of countermeasure techniques. Attackers detect the honeyclient and evade analysis using sophisticated JavaScript code. The evasive code indirectly identifies vulnerable clients by abusing the differences among JavaScript implementations. Attackers deliver malware only to targeted clients on the basis of the evasion results while avoiding honeyclient analysis. Therefore, we are faced with a problem in that honeyclients cannot analyze malicious websites. Nevertheless, we can observe the evasion nature, i.e., the results in accessing malicious websites by using targeted clients are different from those by using honeyclients. In this paper, we propose a method of extracting evasive code by leveraging the above differences to investigate current evasion techniques. Our method analyzes HTTP transactions of the same website obtained using two types of clients, a real browser as a targeted client and a browser emulator as a honeyclient. As a result of evaluating our method with 8,467 JavaScript samples executed in 20,272 malicious websites, we discovered previously unknown evasion techniques that abuse the differences among JavaScript implementations. These findings will contribute to improving the analysis capabilities of conventional honeyclients.

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