What is CVE-2023-24932 vulnerability?
CVE-2023-24932 is a critical security feature bypass vulnerability in the Windows Boot Manager.
It allows an attacker with administrator privileges or physical access to bypass Secure Boot protections. By exploiting this flaw, attackers can execute untrusted software during the boot process, establishing persistence at the firmware level that is invisible to traditional antivirus and EDR solutions. It is famously associated with the BlackLotus UEFI bootkit.
When was it discovered?
CVE-2023-24932 was publicly disclosed by Microsoft on May 9, 2023, following investigations into the BlackLotus bootkit active in the wild.
While patches were released immediately, Microsoft warned that applying the update alone is insufficient; manual steps are required to revoke trust in older, vulnerable boot managers to fully close the vulnerability window.
Affected products & versions
The following table details the affected versions and the associated patch guidance:
Product | Versions Affected | Fixed Versions / Patch Links |
Windows 10 | Version 20H2, 21H2, 22H2 | |
Windows 11 | Version 21H2, 22H2 | |
Windows Server | 2012, 2016, 2019, 2022 |
CVE-2023-24932 technical description
The vulnerability exploits a flaw in how the Windows Boot Manager (bootmgr) validates digital signatures during the startup process.
Attackers utilize a technique often called a "downgrade attack." They bring a legitimate, older version of the Windows Boot Manager that contains the vulnerability and force the system to boot using this vulnerable file. Because the older boot manager is still signed by Microsoft and trusted by Secure Boot, the system allows it to load. Once loaded, the attacker exploits the flaw to execute their own unsigned, malicious kernel driver.
Tactics, techniques & procedures (TTPs)
Attackers, specifically those using BlackLotus, gain initial access (often via other exploits) and elevate to Administrator privileges.
They then mount the EFI System Partition (ESP) and replace the current boot files with the vulnerable Windows boot manager and their malicious bootkit files. Upon reboot, the system loads the compromised environment, typically disabling endpoint security tools like Microsoft Defender before the operating system even starts.
Indicators of compromise
Indicators include unexpected changes to the EFI System Partition, such as the presence of unrecognized .efi files or modified BCD (Boot Configuration Data) stores.
Defenders should watch for the disabling of Memory Integrity (HVCI) or BitLocker, and logs indicating that Secure Boot has been disabled or tampered with.
Known proof-of-concepts & exploits
The BlackLotus bootkit is the primary real-world exploit for this vulnerability.
This malware toolkit, sold on hacking forums, automated the exploitation process, making advanced firmware persistence accessible to cybercriminals. It demonstrated the ability to patch the Windows kernel on the fly to evade detection.
How to detect CVE-2023-24932 vulnerability?
Detection involves auditing the version of the Windows Boot Manager and checking the Secure Boot revocation list (DBX).
Organizations can use tools to query the UEFI revocation list to see if the vulnerable boot manager signatures have been added. If the DBX has not been updated, the system remains vulnerable even if Windows updates are installed.
Impact & risk of CVE-2023-24932 vulnerability
The risk is severe as it undermines the "Root of Trust" for the operating system.
Successful exploitation grants attackers Ring 0 (Kernel) privileges or higher, allowing them to hide from security software, survive OS re-installations, and exfiltrate credentials. It poses a significant threat to high-value targets and critical infrastructure.
Mitigation & remediation strategies
Mitigation is a strict multi-step process. First, apply the May 2023 (or later) Windows security updates.
Second, administrators must manually apply revocation policies to ban the vulnerable boot managers. This involves updating the Secure Boot DBX revocation list. Warning: Performing this step incorrectly can render devices unbootable if they do not have the updated boot manager installed first.
[[FAQ]]CVE-2023-24932 Vulnerability FAQs
[[Q]]
What is CVE-2023-24932 and how does it work?
[[A]]
CVE-2023-24932 is a Secure Boot bypass vulnerability. It works by allowing an attacker to swap the modern, secure bootloader with an older, vulnerable version that is still trusted by the system.
The attacker then exploits this older file to run malicious code before Windows starts.
[[Q]]
How does CVE-2023-24932 infect systems?
[[A]]
It is not a self-spreading virus. An attacker must first gain Administrator access to a system (via phishing, stolen credentials, or other exploits).
Once they have access, they modify the boot partition files to install the exploit.
[[Q]]
Is CVE-2023-24932 still a threat in 2025?
[[A]]
Yes. Because the mitigation requires manual intervention (updating the revocation list) which carries the risk of breaking the boot process, many organizations have hesitated to fully apply the fix.
This leaves a window open for attackers to use downgrade attacks against updated Windows systems.
[[Q]]
How can organizations protect themselves from CVE-2023-24932?
[[A]]
Organizations must apply the latest Windows updates and then carefully follow Microsoft's guidance to update the Secure Boot DBX revocation list.
Using Huntress Managed EDR can help detect the post-exploitation behaviors associated with bootkits.
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