Patches Released by Microsoft to Tackle Two Windows Zero-Day Exploits, as well as 71 Other Vulnerabilities

Microsoft has released patches to address 73 security flaws spanning its software lineup as part of its Patch Tuesday updates for February 2024, including two zero-days that have come under active exploitation. 

Of the 73 vulnerabilities, 5 are rated Critical, 65 are rated Important, and three and rated Moderate in severity. This is in addition to 24 flaws that have been fixed in the Chromium-based Edge browser since the release of the January 2024 Patch Tuesday updates. 

The two flaws that are listed as under active attack at the time of release are below – 

  • CVE-2024-21351 (CVSS score: 7.6) – Windows SmartScreen Security Feature Bypass Vulnerability 
  • CVE-2024-21412 (CVSS score: 8.1) – Internet Shortcut Files Security Feature Bypass Vulnerability

“The vulnerability allows a malicious actor to inject code into SmartScreen and potentially gain code execution, which could potentially lead to some data exposure, lack of system availability, or both,” Microsoft said about CVE-2024-21351. 

Successful exploitation of the flaw could allow an attacker to circumvent SmartScreen protections and run arbitrary code. However, for the attack to work, the threat actor must send the user a malicious file and convince the user to open it. 

CVE-2024-21412, in a similar manner, permits an unauthenticated attacker to bypass displayed security checks by sending a specially crafted file to a targeted user. 

“However, the attacker would have no way to force a user to view the attacker-controlled content.” Redmond noted. “Instead, the attacker would have to convince them to take action by clicking on the file link.” 

CVE-2024-21351 is the second bypass bug to be discovered in SmartScreen after CVE-2023-36025 (CVSS score: 8.8), which was plugged by the tech giant in November 2023. The flaw has since been exploited by multiple hacking groups to proliferate DarkGate, Phemedrone Stealer, and Mispadu. 

Trend Micro, which detailed an attack campaign undertaken by Water Hydra (aka DarkCasino) targeting financial market traders by means of a sophisticated zero-day attack chain leveraging CVE-2024-21412, described CVE-2024-21412 as a bypass for CVE-2023-36025, thereby enabling threat actors to evade SmartScreen checks. 

Water Hydra, first detected in 2021, has a track record of launching attacks against banks, cryptocurrency platforms, trading services, gambling sites, and casinos to deliver a trojan called DarkMe using zero-day exploits, including the WinRAR flaw that came to light in August 2023 (CVE-2023-38831, CVSS score: 7.8). 

Late last year, Chinese cybersecurity company NSFOCUS graduated the “economically motivated” hacking group to an entirely new advanced persistent threat (APT). 

“In January 2024, Water Hydra updated its infection chain exploiting CVE-2024-21412 to execute a malicious Microsoft Installer File (.MSI), streamlining the DarkMe infection process,” Trend Micro said. 

Both vulnerabilities have since been added to the Known Exploited Vulnerabilities (KEV) catalogue by the U.S. Cybersecurity and Infrastructure Security Agency (CISA), urging federal agencies to apply the latest updates by March 5, 2024. 


Also patched by Microsoft are five critical flaws: 

  • CVE-2024-20684 (CVSS score: 6.5) – Windows Hyper-V Denial of Service Vulnerability 
  • CVE-2024-21357 (CVSS score: 7.5) – Windows Pragmatic General Multicast (PGM) Remote Code Execution Vulnerability 
  • CVE-2024-21380 (CVSS score: 8.0) – Microsoft Dynamics Business Central/NAV Information Disclosure Vulnerability 
  • CVE-2024-21410 (CVSS score: 9.8) – Microsoft Exchange Server Elevation of Privilege Vulnerability 
  • CVE-2024-21413 (CVSS score: 9.8) – Microsoft Outlook Remote Code Execution Vulnerability 


“CVE-2024-21410 is an elevation of privilege vulnerability in Microsoft Exchange Server,” Satnam Narang, senior staff research engineer at Tenable, said in a statement. “This flaw is more likely to be exploited by attackers according to Microsoft.” 

“Exploiting this vulnerability could result in the disclosure of a targeted user’s Net-New Technology LAN Manager (NTLM) version 2 hash, which could be relayed back to a vulnerable Exchange Server in an NTLM relay or pass-the-hash attack, which would allow the attacker to authenticate as the targeted user.” 

The security update further resolves 15 remote code execution flaws in Microsoft WDAC OLE DB provider for SQL Server that an attacker could exploit by tricking an authenticated user into attempting to connect to a malicious SQL server via OLEDB. 

Rounding off the patch is a fix for CVE-2023-50387 (CVSS score: 7.5), a 24-year-old design flaw in the DNSSEC specification that can be abused to exhaust CPU resources and stall DNS resolvers, resulting in a denial-of-service (DoS). 

The vulnerability has been codenamed KeyTrap by the National Research Center for Applied Cybersecurity (ATHENE) in Darmstadt. 

“[The researchers] demonstrated that just with a single DNS packet the attack can exhaust the CPU and stall all widely used DNS implementations and public DNS providers, such as Google Public DNS and Cloudflare,” ATHENE said. “In fact, the popular BIND 9 DNS implementation can be stalled for as long as 16 hours.” 


Software Patches from Other Vendors 

In addition to Microsoft, security updates have also been released by other vendors over the past few weeks to rectify several vulnerabilities, including: 


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