Compass Security Blog

Offensive Defense

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Microsoft BitLocker Bypasses are Practical

In this blog article, we would like to share key insights from the “Defeating Microsoft’s Default BitLocker Implementation” security training by Hands-On Security and emphasize the potential risks and consequences associated with this attack technique. Our target audience includes businesses looking to safeguard sensitive data on their Windows devices, as well as individuals with an elevated requirement for protecting their data.

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Device Code Phishing – Add Your Own Sign-In Methods on Entra ID

TL;DR An attacker is able to register new security keys (FIDO) or other authentication methods (TOTP, Email, Phone etc.) after a successful device code phishing attack. This allows an attacker to backdoor the account (FIDO) or perform the self-service password reset for the account with the newly registered sign-in methods. Microsoft deemed this not a vulnerability.

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Microsoft Teams Covert Channels Research

With the rise of remote working, Microsoft Teams has become the de-facto standard for video conferences, chat, and collaboration. The nature of the Teams architecture are some central systems that route information between parties. With that comes that Teams client software must be allowed to communicate to the Internet. Microsoft even recommends letting Teams traffic bypass inspection proxies for compatibility reasons. Its network communication pattern has significant overlap with malicious C2 traffic und thus it is nearly impossible for blue teams to spot adversary communication. Therefore, Teams is an interesting candidate to be abuses for C2 traffic. Thus, we put some research into this.

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