Backdooring MS Office documents with secret master keys

Presented at BSidesLV 2015, Aug. 5, 2015, noon (25 minutes)

Recent MS Office documents are normally encrypted very strongly, making them difficult to brute force. However, there are techniques an attacker can use to secretly backdoor these encrypted documents to make them trivial to decrypt. Cloud environments may be more dangerous than thought as it is not possible for users to confirm the security of their encryption and it would be easy for cloud providers (or advanced attackers with access to those cloud providers) to backdoor encryption in undetectable ways. I believe that this is a serious problem that the security industry needs to consider.


Presenters:

  • Shigeo Mitsunari
    Shigeo Mitsunari is a software developer and researcher. He is interested in cryptography, in particular, pairing-based cryptography and its implementation. He developes a x86/x64 JIT assembler Xbyak and very fast C++ pairing library which are open source projects. He was received MITOH Super Creator by IPA in 2003, the Chairman Awards by Information Promotion consortium in 2005, the Best paper award by IEICE in 2010.
  • Yoshinori Takesako - chairperson - SECCON
    Yoshinori Takesako is the executive committee chairperson, organizer, and challenge creator of the SECCON CTF contests that are held several times a year throughout Japan including large international online and in-person contests. He is also on the OWASP Japan advisory board, the review board for the CODE BLUE conference, a Microsoft MVP of Developer Security, the leader of the Shibuya Perl Mongers group, and has been designated an expert in ISO/IEC JTC 1/SC 22 programming languages such as C# and other scripting languages. He has also presented at information security conferences such as HITCON in 2011 "Disassembling Flash Lite 3.0 SWF Files", and OWASP AppSec APAC 2014 "Secure escaping method for the age of HTML5", and has published some books and papers:"Reading ECMA-262 Edition 5.1" and "How to Execute Arbitrary Code on x86 JIT Compliers" etc.

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