Everyday is lazarus.dayβ

Lazarus and the FudModule Rootkit: Beyond BYOVD with an Admin-to-Kernel Zero-Day

2024-02-28, Avast
#FudModule #BYOVD #CVE-2024-21338


Key Points
- Avast discovered an in-the-wild admin-to-kernel exploit for a previously unknown zero-day vulnerability in the appid.sys AppLocker driver.
- Thanks to Avast’s prompt report, Microsoft addressed this vulnerability as CVE-2024-21338 in the February Patch Tuesday update.
- The exploitation activity was orchestrated by the notorious Lazarus Group, with the end goal of establishing a kernel read/write primitive.
- This primitive enabled Lazarus to perform direct kernel object manipulation in an updated version of their data-only FudModule rootkit, a previous version of which was analyzed by ESET and AhnLab.
- After completely reverse engineering this updated rootkit variant, Avast identified substantial advancements in terms of both functionality and stealth, with four new – and three updated – rootkit techniques.
- In a key advancement, the rootkit now employs a new handle table entry manipulation technique in an attempt to suspend PPL (Protected Process Light) protected processes associated with Microsoft Defender, CrowdStrike Falcon, and HitmanPro.
- Another …