Source URL: https://www.microsoft.com/en-us/security/blog/2025/04/08/exploitation-of-clfs-zero-day-leads-to-ransomware-activity/
Source: Microsoft Security Blog
Title: Exploitation of CLFS zero-day leads to ransomware activity
Feedly Summary: Microsoft Threat Intelligence Center (MSTIC) and Microsoft Security Response Center (MSRC) have discovered post-compromise exploitation of a newly discovered zero-day vulnerability in the Windows Common Log File System (CLFS) against a small number of targets. Microsoft released security updates to address the vulnerability, tracked as CVE 2025-29824, on April 8, 2025.
The post Exploitation of CLFS zero-day leads to ransomware activity appeared first on Microsoft Security Blog.
AI Summary and Description: Yes
Summary: Microsoft has identified and patched a zero-day vulnerability (CVE-2025-29824) affecting the Windows Common Log File System (CLFS) that is being exploited by the PipeMagic malware to escalate privileges and facilitate ransomware attacks. This vulnerability allows an attacker to gain elevated privileges from a standard user account, making it valuable for threat actors looking to deploy ransomware across environments.
Detailed Description:
The text discusses a critical security vulnerability in Microsoft’s Windows operating system and provides an in-depth analysis of how this vulnerability is being exploited by malicious actors. The main points include:
– **Vulnerability Overview**:
– The vulnerability tracked as CVE-2025-29824 allows standard user accounts to escalate to privileged accounts, enhancing attackers’ capability to spread ransomware.
– Microsoft released a patch for this vulnerability on April 8, 2025.
– **Exploit Mechanism**:
– The exploitation is carried out through the PipeMagic malware which allows attackers to first compromise a device, then exploit the CLFS vulnerability.
– The attack chain begins when the target executes a malicious MSBuild file downloaded via the certutil utility, leading to the exploitation of the CLFS driver.
– **Targets**:
– The primary sectors affected include IT companies, real estate, finance in Venezuela, software companies in Spain, and retail in Saudi Arabia.
– **Post-Exploitation Activity**:
– Following the exploitation, the malware was observed to inject a payload into critical Windows processes such as ‘winlogon.exe’.
– The operation culminates in ransomware deployment, encrypting files and dropping ransom notes.
– **Mitigation Strategies**:
– Organizations are encouraged to apply the security patch promptly to mitigate the risks posed by this vulnerability.
– Other recommendations include enabling cloud-delivered protection, utilizing endpoint detection and response in block mode, and turning on attack surface reduction rules.
– **Indicators of Compromise**:
– The text lists specific indicators that security professionals should monitor, including unusual process command lines and suspicious access to sensitive areas like LSASS.
– **Threat Intelligence Sharing**:
– Microsoft emphasizes the importance of sharing this threat intelligence with customers to bolster their defenses against similar attacks.
In summary, the blog post serves a vital role in informing IT professionals about the dynamics of current threat activities, the significance of timely patching, and the importance of layered security mechanisms in preventing and responding to ransomware attacks.