DeeperML

Microsoft has uncovered 20 previously unknown vulnerabilities in the GRUB2, U-Boot, and Barebox open-source bootloaders using its AI-powered Security Copilot. These bootloaders are critical components, with GRUB2 commonly used in Linux distributions like Ubuntu, and U-Boot and Barebox prevalent in embedded and IoT devices. The identified vulnerabilities include integer and buffer overflows in filesystem parsers, command flaws, and a side-channel in cryptographic comparison, potentially enabling threat actors to gain control and execute arbitrary code.

Water Gamayun, a suspected Russian hacking group, has been linked to the exploitation of CVE-2025-26633 (MSC EvilTwin) to deploy SilentPrism and DarkWisp. The group uses malicious provisioning packages, signed .msi files, and Windows MSC files to deliver information stealers and backdoors. These backdoors, SilentPrism and DarkWisp, enable persistence, system reconnaissance, data exfiltration, and remote command execution. The threat actors transitioned to their own infrastructure for staging and command-and-control purposes after using a GitHub repository to push various kinds of malware families.

ImgSrc: www.microsoft.c

References :

• The Hacker News: The threat actors behind the zero-day exploitation of a recently-patched security vulnerability in Microsoft Windows have been found to deliver two new backdoors called SilentPrism and DarkWisp. The activity has been attributed to a suspected Russian hacking group called Water Gamayun, which is also known as EncryptHub and LARVA-208. "The threat actor deploys payloads primarily by means of
• Microsoft Security Blog: Using Microsoft Security Copilot to expedite the discovery process, Microsoft has uncovered several vulnerabilities in multiple open-source bootloaders impacting all operating systems relying on Unified Extensible Firmware Interface (UEFI) Secure Boot. Through a series of prompts, we identified and refined security issues, ultimately uncovering an exploitable integer overflow vulnerability in the GRUB2, U-boot, and Barebox bootloaders. The post appeared first on .
• bsky.app: Microsoft used its AI-powered Security Copilot to discover 20 previously unknown vulnerabilities in the GRUB2, U-Boot, and Barebox open-source bootloaders. https://www.bleepingcomputer.com/news/security/microsoft-uses-ai-to-find-flaws-in-grub2-u-boot-barebox-bootloaders/
• BleepingComputer: Microsoft uses AI to find flaws in GRUB2, U-Boot, Barebox bootloaders

Classification:

• HashTags: #Microsoft #Vulnerabilities #Bootloaders
• Company: Microsoft
• Target: UEFI Secure Boot
• Attacker: Water Gamayun
• Product: Security Copilot
• Feature: Security Copilot
• Malware: SilentPrism and DarkWisp
• Type: Vulnerability
• Severity: Major