Windows

Security Advisory

Decade-Old Threat: CVE-2018-8639 Still Poses Risks to Unpatched Windows Systems 

CVE-2018-8639 is a privilege escalation flaw in the Win32k component of Microsoft Windows that lets attackers run any code in kernel mode. This vulnerability, which was first fixed by Microsoft in December 2018, still poses a risk to unpatched computers.

OEM Microsoft 
Severity High 
CVSS 7.8 
CVEs CVE-2018-8639 
Exploited in Wild Yes 
Patch/Remediation Available Yes 
Advisory Version 1.0 

Overview on Vulnerability

The vulnerability gives hackers the ability to install persistent malware, get around security measures, and alter system operations covertly. The Cybersecurity and Infrastructure Security Agency (CISA) has included this vulnerability in its Known Exploited Vulnerabilities (KEV) catalog, further highlighting its ongoing threat. 

Vulnerability Name CVE ID Product Affected Severity 
 Privilege Escalation Vulnerability  CVE-2018-8639  Windows  High 

Technical Summary 

The vulnerability exists within the Win32k.sys driver, which handles graphical user interface (GUI) interactions.

Designated as CWE-404: Improper Resource Shutdown or Release, the flaw enables authenticated local attackers to improperly release system resources, leading to privilege escalation. Exploiting this vulnerability grants kernel-mode execution rights, allowing attackers to bypass security mechanisms, install persistent malware, and manipulate system functions without detection. 

CVE ID System Affected Vulnerability Details Impact 
CVE-2018-8639 Windows 7, 8.1, 10, RT 8.1, Windows Server 2008, 2008 R2, 2012, 2012 R2, 2016, 2019  Improper Resource Shutdown or Release in Win32k.sys driver, enabling privilege escalation. System compromise, unauthorized access, potential malware persistence 

Remediation: 

  • Organizations and individuals must apply Microsoft’s security updates released in December 2018 (KB4483235) to mitigate the risk. 
  • Additionally, it is essential to apply all available updates from Windows to ensure comprehensive protection against known vulnerabilities.  

General Recommendations: 

  • Implement network segmentation to isolate critical assets and minimize the impact of potential security breaches. 
  • Adopting the principle of least privilege (PoLP) to limit user access. 
  • Continuous monitoring of anomalous kernel-mode activities. 

Conclusion: 

Unpatched Windows systems are particularly vulnerable, especially in industrial control systems (ICS) and healthcare facilities where obsolete software is ubiquitous. While Microsoft has fixed the issue, firms that rely on legacy systems must implement additional security measures. Cyber adversaries are always refining their exploitation techniques, making proactive security strategies critical to reducing risk. 

References: 

  • https://nvd.nist.gov/vuln/detail/cve-2018-8639  
  • https://github.com/ze0r/CVE-2018-8639-exp 

Security Advisory

Microsoft Updates Patch Tuesday for Feb 2025; Address 67 Vulnerabilities, Includes 2 Exploited Zero-Days 

Summary

Microsoft’s February 2025 Patch Tuesday addresses multiple security vulnerabilities, including four zero-days, with two actively exploited in the wild. This update covers a total of 67 security flaws, with three classified as critical Remote Code Execution (RCE) vulnerabilities.  

Microsoft  issued a revision for an older zero-day that threatens the latest Windows desktop and server versions.

OEM Microsoft 
Severity Critical 
Date of Announcement 2025-02-11
No. of Vulnerabilities Patched 67 
Actively Exploited Yes 
Exploited in Wild Yes 
Advisory Version 1.0 

Overview 

The affected products include Windows, Microsoft Office, Microsoft Surface, and various network services. Organizations are strongly advised to apply these patches immediately to mitigate security risks and potential cyberattacks. 

  • 63 Microsoft CVEs addressed 
  • 4 non-Microsoft CVEs included 

The highlighted vulnerabilities include 4 zero-day flaws, 2 of which are currently being actively exploited. 

Vulnerability Name CVE ID Product Affected Severity CVSS Score 
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability CVE-2025-21418 Windows High 7.8 
Windows Storage Elevation of Privilege Vulnerability  CVE-2025-21391 Windows High 7.1 
Microsoft Surface Security Feature Bypass Vulnerability CVE-2025-21194 Windows High  7.1 
NTLM Hash Disclosure Spoofing Vulnerability CVE-2025-21377 Windows Medium  6.5 

Technical Summary 

CVE ID System Affected Vulnerability Details Impact 
  CVE-2025-21418  Windows server and Windows 10 & 11  Windows ancillary function driver for winsock elevation of privilege vulnerability enables attackers to escalate privileges to SYSTEM level. Specific exploitation details are not disclosed.    Unauthorized access with SYSTEM privileges.  
  CVE-2025-21391  Windows server and Windows 10 & 11 Windows storage elevation of privilege vulnerability allows attackers to delete targeted files on a system, potentially leading to service unavailability. Does not expose confidential data.    Deletion of critical data, leading to service disruption. 
  CVE-2025-21194    Microsoft Surface    Microsoft surface security feature bypass vulnerability allows attackers to bypass UEFI protections, compromising the secure kernel. Likely related to “PixieFail” vulnerabilities affecting the IPv6 network stack in Tianocore’s EDK II firmware.    Bypass of security features, potentially compromising system integrity. 
 CVE-2025-21377  Windows server and Windows 10 & 11 NTLM hash disclosure spoofing vulnerability exposes NTLM hashes when a user interacts with a malicious file. Simply selecting or right-clicking a file could trigger a remote connection, allowing an attacker to capture NTLM hashes for cracking or pass-the-hash attacks.   Potential for attackers to authenticate as the user, leading to unauthorized access. 

Source:  Microsoft       

In addition to the actively exploited vulnerabilities, several other critical flaws were also addressed: 

  • CVE-2025-21376: A Windows Lightweight Directory Access Protocol (LDAP) RCE vulnerability that could allow attackers to execute arbitrary code remotely. 
  • CVE-2025-21379: A DHCP Client Service RCE vulnerability that may enable remote attackers to execute code with elevated privileges. 
  • CVE-2025-21381: An RCE vulnerability in Microsoft Excel that could be triggered through malicious spreadsheet files. 

Remediation: 

  • Apply Updates: Immediately install the February 2025 Patch Tuesday updates to address these vulnerabilities. 

Conclusion: 

The February 2025 Patch Tuesday release addresses critical security vulnerabilities, including actively exploited zero-days. Timely application of these updates is essential to protect systems from potential threats. Organizations should review the affected products and implement the necessary patches and mitigations to maintain security integrity. 

The attack vector is local, meaning the attacker needs local access — physically or remotely, using SSH method without user interaction and if successful in exploiting, can give the attacker system privileges.

References: 

Security Advisory

Zero-Day Vulnerability in Windows (CVE-2024-49138): PoC Released, Exploited in the Wild

Summary

OEM

Microsoft

Severity

Critical

CVSS Score

7.8

CVE

CVE-2024-49138

Exploited in Wild

Yes

Patch/Remediation Available

Yes

Advisory Version

1.0

Publicly POC Available

Yes


Overview

The vulnerability CVE-2024-49138, affecting the Windows Common Log File System (CLFS) driver, enables attackers to gain SYSTEM privileges via a heap-based buffer overflow. Security researcher MrAle_98 published a proof-of-concept (PoC) exploit, increasing its potential misuse.

Vulnerability Name

CVE ID

Product Affected

Severity

CLFS Privilege Escalation

CVE-2024-49138

Microsoft Windows

High

Technical Summary

CVE-2024-49138 is a heap-based buffer overflow vulnerability in the Windows Common Log File System (CLFS) driver, allowing attackers to escalate privileges to SYSTEM level. It affects a wide range of Windows systems, including the latest versions, such as Windows 11 23H2. Initially discovered by CrowdStrike’s Advanced Research Team, Microsoft confirmed active exploitation prior to its December 2024 patch release. Security researcher MrAle_98 published a proof-of-concept exploit on GitHub, increasing the likelihood of threat actor replication and exploitation.

CVE ID

System Affected

Vulnerability Details

Impact

CVE-2024-49138

Windows 10, Windows 11, Windows Server 2008–2025

Heap buffer overflow in CLFS driver enabling SYSTEM access. Exploited in the wild and PoC publicly released.

Enables attackers to elevate their privileges to SYSTEM level, granting them complete control over an affected device.

Remediations

  1. Update Systems: Apply Microsoft’s December 2024 patches without delay.
  2. Monitor Systems: Be alert for unusual privilege escalations or indicators of compromise.
  3. Limit Access: Implement robust access controls and harden systems.

Conclusion:

The public release of a proof-of-concept exploit heightens risks, making immediate patching essential. Organizations must prioritize updates, monitor for exploitation, and implement strict access controls.

References

Security Advisory

Critical Security Updates: Microsoft Jan 2025 Patch Tuesday Fixes 8 Zero-Days & 159 Vulnerabilities 

Summary 

Microsoft has released its January 2025 Patch Tuesday updates, delivering critical fixes. Key products impacted include Windows Telephony Service, Windows Digital Media, and MSMQ, among others.

Key take away:

  • Microsoft addressed 159 vulnerabilities across multiple products, including eight zero-day flaws, with three actively exploited in the January 2025 Patch Tuesday updates.
  • Key vulnerabilities include privilege escalation flaws in Hyper-V and remote code execution bugs in Microsoft Excel.
  • This marks highest number of fixes in a single month since at least 2017.
OEM  Microsoft 
Severity  Critical 
Date of Announcement  2025-01-14 
No. of Vulnerabilities Patched  159 
Actively Exploited  yes 
Exploited in Wild  Yes 
Advisory Version  1.0 

Overview 

Critical updates were issued for Windows Hyper-V, Windows Themes, Microsoft Access, and Windows App Package Installer. The vulnerabilities include elevation of privilege, remote code execution, and spoofing attacks, impacting various systems. The patch targets a range of critical issues across Microsoft products, categorized as follows: 

  • 58 Remote Code Execution (RCE) Vulnerabilities 
  • 40 Elevation of Privilege (EoP) Vulnerabilities 
  • 22 Information Disclosure Vulnerabilities 
  • 20 Denial of Service (DoS) Vulnerabilities 
  • 14 Security Feature Bypass 
  • 5 Spoofing Vulnerabilities 

The highlighted vulnerabilities include 8 zero-day flaws, 3 of which are currently being actively exploited. 

Vulnerability Name  CVE ID  Product Affected  Severity  CVSS Score 
Elevation of privilege vulnerability   CVE-2025-21333,  CVE-2025-21334,  CVE-2025-21335  Windows  High  7.8 
Elevation of Privilege Vulnerability  CVE-2025-21275  Windows  High  7.8 
Remote Code Execution Vulnerability  CVE-2025-21186,CVE-2025-21366, CVE-2025-21395  Windows  High  7.8 
Spoofing Vulnerability  CVE-2025-21308  Windows  Medium  6.5 

Technical Summary 

CVE ID  System Affected  Vulnerability Details  Impact 
 CVE-2025-21333,  CVE-2025-21334,  CVE-2025-21335   Windows Hyper-V NT Kernel  No information has been released on how elevation of privilege vulnerabilities in Windows Hyper-V NT Kernel Integration VSP, which allow attackers to gain SYSTEM privileges, were exploited in attacks, as they were disclosed anonymously.     Allow attackers to gain SYSTEM privileges 
  CVE-2025-21275   Windows App Package Installer  Elevation of privilege vulnerability in the Windows App Package Installer, potentially leading to SYSTEM privileges.    Attackers could gain SYSTEM privileges 
 CVE-2025-21186,CVE-2025-21366, CVE-2025-21395    Microsoft Access   Remote code execution vulnerabilities in Microsoft Access, exploitable via specially crafted Access documents.    Remote Code Execution 
 CVE-2025-21308    Windows Themes  Spoofing vulnerability in Windows Themes; viewing a specially crafted theme file in Windows Explorer can lead to NTLM credential theft.    NTLM credential theft 

Source:  Microsoft       

Additional Critical Patches Address High-Severity Vulnerabilities 

  • Eight of this month’s patches address Virtual Secure Mode components, requiring administrators to follow Microsoft’s guidance for updating virtualization-based security (VBS) issues. (CVE-2025-21280, CVE-2025-21284, CVE-2025-21299, CVE-2025-21321, CVE-2025-21331, CVE-2025-21336, CVE-2025-21340, CVE-2025-21370). 
  • Windows NTLM V1 Elevation of Privilege Vulnerability (CVE-2025-21311). 
  • Windows OLE Remote Code Execution Vulnerability (CVE-2025-21298). 

Remediation: 

  • Apply Updates: Immediately install the January 2025 Patch Tuesday updates to address these vulnerabilities. 
  • Disable NTLM: For CVE-2025-21308, consider disabling NTLM or enabling the “Restrict NTLM: Outgoing NTLM traffic to remote servers” policy to mitigate the risk.  
  • Exercise Caution with Untrusted Files: Avoid opening or interacting with files from untrusted sources, especially those with extensions associated with Microsoft Access. 

Conclusion: 

The January 2025 Patch Tuesday release addresses critical vulnerabilities that could allow attackers to gain elevated privileges, execute arbitrary code, or steal credentials. Prompt application of these updates is essential to maintain system security. Additionally, implementing recommended mitigations, such as disabling NTLM, can provide further protection against potential exploits. 

References: 

https://msrc.microsoft.com/update-guide/releaseNote/2025-Jan

Security Advisory

Critical Windows Privilege Escalation Vulnerability with Public Exploit

Cybersecurity researchers reported a critical Windows privilege escalation vulnerability, identified as CVE-2024-43641 affecting Microsoft Windows. This flaw, which affects various editions of Windows Server 2025, Windows 10, and Windows 11, has been assigned a CVSS v3.1 score of 7.8, indicating high severity.

Summary 

OEM Microsoft 
Severity High 
CVSS 7.8 
CVEs CVE-2024-43641 
Exploited in Wild No 
Patch/Remediation Available Yes 
Advisory Version 1.0 

Overview 

A significant Windows Registry Elevation of Privilege vulnerability, identified as CVE-2024-43641, affects multiple editions of Windows. A recently released Proof-of-Concept (PoC) exploit demonstrates how attackers can exploit this flaw to gain elevated privileges. 

Vulnerability Name CVE ID Product Affected Severity 
Windows Registry Elevation of Privilege Vulnerability  CVE-2024-43641  Windows    High 

Technical Summary 

The vulnerability, CVE-2024-43641, exploits a design flaw in Windows registry hive memory management, specifically during a double-fetch process under memory pressure. This flaw allows malicious SMB servers to respond with differing data for consecutive read requests, breaking kernel assumptions and enabling privilege escalation to SYSTEM level. Key technical details are as follows: 

CVE ID System Affected Vulnerability Details Impact 
CVE-2024-43641 Windows 10, Windows 11, Windows Server 2008–2025 The vulnerability involves improper handling of registry hive memory management under memory pressure. A malicious SMB server can respond with differing data to consecutive read requests, breaking kernel assumptions. Exploitation leverages a “False File Immutability” (FFI) condition. Allows attackers to escalate privileges, execute arbitrary code, and compromise system integrity. 

Remediation: 

  • Apply Patches: Users and system administrators are strongly advised to promptly apply the latest security updates. 
  • Monitor Activity: 
  • Monitor logs for suspicious activity related to registry operations. 
  • The cybersecurity community is actively monitoring the situation for any indications of active exploitation in the wild. 

Conclusion: 

CVE-2024-43641 is a high-severity vulnerability with a publicly available PoC exploit. It is crucial to apply security patches immediately and follow best practices to mitigate the risk of exploitation. Organizations must stay alert and monitor ongoing developments to ensure complete protection against this emerging threat. 

References: 

Security Advisory

Exploit Proof-of-Concept Released for Windows Lightweight Directory Access Protocol (LDAP CVE-2024-49113 )

CVE-2024-49113 LDAP

Continue Reading
Security Advisory

Microsoft December 2024 Patch Tuesday: Critical Fixes for Zero-Day and Remote Code Execution

Summary

OEM

Microsoft

Severity

High

Date of Announcement

2024-12-12

NO. of Vulnerabilities Patched

71

Actively Exploited

01

Exploited in Wild

Yes

Advisory Version

1.0

Overview

Microsoft released updates addressing 71 vulnerabilities across its product suite, including 1 actively exploited zero-day vulnerability. Critical patches include fixes for remote code execution (RCE) flaws in Windows TCP/IP and Windows Common Log File System (CLFS). Immediate attention is required for systems running Windows Server, Microsoft Exchange, and other affected components. The patch targets a range of critical issues across Microsoft products, categorized as follows:

  • 30 Remote Code Execution (RCE) Vulnerabilities
  • 27 Elevation of Privilege (EoP) Vulnerabilities
  • 7 Information Disclosure Vulnerabilities
  • 4 Denial of Service (DoS) Vulnerabilities
  • 1Defense-in-depth improvement
  • 1 Spoofing Vulnerabilities

The highlighted vulnerabilities include one zero-day flaw and critical RCE vulnerabilities, one of which is currently being actively exploited.

Vulnerability Name

CVE ID

Product Affected

Impact

CVSS Score

Unauthenticated Remote Code Execution in Windows LDAP

CVE-2024-49112 

Windows

Critical

9.8

Remote Code Execution in Windows Hyper-V

CVE-2024-49117

Windows

High

8.8

Remote Code Execution via Use-After-Free in Remote Desktop Services

CVE-2024-49132

Windows

High

8.1

Windows Common Log File System Driver Elevation of Privilege Vulnerability

CVE-2024-49138

Windows

High

7.8

Technical Summary

CVE ID

System Affected

Vulnerability Details

Impact

CVE-2024-49112 

Microsoft Windows Lightweight Directory Access Protocol (LDAP)

This vulnerability allows attackers to execute arbitrary code at the LDAP service level by sending specially crafted LDAP calls to a Windows Domain Controller. While Microsoft recommends disconnecting Domain Controllers from the Internet as a mitigation, applying the patch is the best course of action.

Remote Code Execution

CVE-2024-49117

Microsoft Windows Hyper-V

This vulnerability can be exploited by an authenticated attacker to execute code on the host operating system from a guest virtual machine. Cross-VM attacks are also possible. Although the attacker must have basic authentication, the vulnerability poses significant risks to virtualized environments.

Remote Code Execution

CVE-2024-49132

Microsoft Windows Remote Desktop Services

An attacker can exploit a use-after-free memory condition in Remote Desktop Gateway, allowing RCE. Exploitation requires precise timing, which makes this an advanced attack. Successful exploitation grants attackers control over the affected system.

Allows an attacker to execute remote code on systems using Remote Desktop Gateway

CVE-2024-49138

Windows Common Log File System Driver

This critical security flaw affects the Windows Common Log File System Driver and is classified as an Elevation of Privilege vulnerability.

It allows attackers to gain SYSTEM privileges on Windows devices, potentially giving them full control over the affected system.

Additional Critical Patches Address High-Severity Vulnerabilities

  • These are the eight other critical vulnerabilities that are rated 8.1 on the CVSS scale in Remote Desktop Services (CVE-2024-49116, CVE-2024-49108, CVE-2024-49106, CVE-2024-49115, CVE-2024-49128, CVE-2024-49123, CVE-2024-49120, CVE-2024-49119).
  • Windows Mobile Broadband Driver Elevation of Privilege Vulnerability (CVE-2024-49077).
  • Windows Mobile Broadband Driver Elevation of Privilege Vulnerability (CVE-2024-49132).

Remediation

  • Ensure all December 2024 Patch Tuesday updates are applied promptly.
  • Implement a routine patch management process to regularly check for and apply the latest Microsoft security updates and patches for all affected products.
  • Create and test an incident response plan with defined communication channels and responsibilities to ensure readiness for any security breaches.

References

https://msrc.microsoft.com/update-guide/releaseNote/2024-Dec

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