Microsoft Patches Zero-Day Flaw Exploited by North Korea’s Lazarus Group
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2024-21338 | Local Privilege Escalation in Microsoft Windows Kernel via Exposed IOCTL (CVE-2024-21338) CVE-2024-21338 is a local privilege escalation flaw in the Microsoft Windows kernel caused by an exposed IOCTL with insufficient access control (CWE-822): a low-privileged process running locally can issue specially crafted requests to a kernel interface without proper authorization checks. Public research (including Avast's analysis of Lazarus Group's FudModule rootkit) ties the vulnerable component to the Windows AppLocker/AppID driver and shows the bug was exploited as an admin-to-kernel zero-day, letting an attacker with a foothold on a machine gain kernel-level privileges and full control of the host. Because it requires only local access, it is typically chained after initial access or malware delivery, and CISA notes known ransomware use alongside exploitation by North Korea's Lazarus Group. Any organization or device running Windows 10 (1809, 21H2, 22H2), Windows 11 (21H2, 22H2, 23H2), or Windows Server 2019/2022 (including 2022 23H2) is affected until patched. The bug was added to the CISA Known Exploited Vulnerabilities catalog on 2024-03-04 after in-the-wild exploitation and was fixed in Microsoft's March 2024 Patch Tuesday release; EPSS places the 30-day exploitation probability at roughly 60% (99th percentile). Do: Apply Microsoft's March 2024 (or later) cumulative security updates to every listed Windows 10, Windows 11, and Windows Server 2019/2022 system, and verify the installed build includes the March 2024 fixes before closing the KEV entry; if patches are unavailable, follow CISA's required action to apply vendor mitigations or discontinue use. Because this is a local-only escalation commonly chained after initial access, prioritize workstations and servers where untrusted users or code run locally. Hunt for Lazarus/FudModule and BYOVD-related indicators per Avast's published research on hosts of interest. | 7.8 | 60% | KEV ransomware PoC ×3 |
| masson the order of 1 billion devices (essentially the entire supported Windows 10/11 and Windows Server 2019/2022 installed base) | |
| CVE-2024-38193 | Use-After-Free Privilege Escalation in Microsoft Windows WinSock Driver (afd.sys) The Windows Ancillary Function Driver for WinSock (afd.sys) contains a use-after-free flaw (CWE-416) that allows a local attacker to escalate privileges. An attacker who can already execute code on a Windows host — typically after gaining initial access via phishing, malware, or chaining with another vulnerability — triggers the bug to gain SYSTEM-level privileges, giving them near-full control of the machine. Any Windows host running an affected build is exposed to the flaw, though it requires local code execution and is not remotely exploitable on its own. Exploitation is confirmed in the wild: CISA added the CVE to the KEV catalog on 2024-08-13 and Microsoft shipped fixes in its August 2024 security updates, while the ransomware association is currently listed as unknown. EPSS is elevated at 28.5% (98th percentile), indicating a high likelihood of continued exploitation over the next 30 days. Do: Apply Microsoft's August 2024 Windows cumulative security updates (released 2024-08-13) across all Windows clients and servers, prioritizing multi-user hosts such as RDS/VDI servers and jump boxes where local code execution by low-privileged users is more likely. After patching, verify installed build numbers and hunt for signs of local privilege escalation, per CISA's KEV required action to apply vendor mitigations or discontinue use. Keep the host within your KEV remediation SLA, as listing in the catalog signals active exploitation. | 7.8 | 29% | KEV PoC |
| mass>1 billion Windows endpoints worldwide, i.e., effectively every unpatched Windows client or server |
Full article413 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananAug 19, 2024Vulnerability / Zero-Day
A newly patched security flaw in Microsoft Windows was exploited as a zero-day by Lazarus Group, a prolific state-sponsored actor affiliated with North Korea.
The security vulnerability, tracked as CVE-2024-38193 (CVSS score: 7.8), has been described as a privilege escalation bug in the Windows Ancillary Function Driver (AFD.sys) for WinSock.
"An attacker who successfully exploited this vulnerability could gain SYSTEM privileges," Microsoft said in an advisory for the flaw last week. It was addressed by the tech giant as part of its monthly Patch Tuesday update.
Credited with discovering and reporting the flaw are Gen Digital researchers Luigino Camastra and Milánek. Gen Digital owns a number of security and utility software brands like Norton, Avast, Avira, AVG, ReputationDefender, and CCleaner.
"This flaw allowed them to gain unauthorized access to sensitive system areas," the company disclosed last week, adding it discovered the exploitation in early June 2024. "The vulnerability allowed attackers to bypass normal security restrictions and access sensitive system areas that most users and administrators can't reach."
The cybersecurity vendor further noted that the attacks were characterized by the use of a rootkit called FudModule in an attempt to evade detection.
While the exact technical details associated with the intrusions are presently unknown, the vulnerability is reminiscent of another privilege escalation flaw that Microsoft fixed in February 2024 and was also weaponized by the Lazarus Group to drop FudModule.
Specifically, it entailed the exploitation of CVE-2024-21338 (CVSS score: 7.8), a Windows kernel privilege escalation flaw rooted in the AppLocker driver (appid.sys) that makes it possible to execute arbitrary code such that it sidesteps all security checks and runs the FudModule rootkit.
Both these attacks are notable because they go beyond a traditional Bring Your Own Vulnerable Driver (BYOVD) attack by taking advantage of a security flaw in a driver that's already installed on a Windows host as opposed to "bringing" a susceptible driver and using it to bypass security measures.
Previous attacks detailed by cybersecurity firm Avast revealed that the rootkit is delivered by means of a remote access trojan known as Kaolin RAT.
"FudModule is only loosely integrated into the rest of Lazarus' malware ecosystem," the Czech company said at the time, stating "Lazarus is very careful about using the rootkit, only deploying it on demand under the right circumstances."
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