Wednesday, May 29, 2024

PoC Exploit Released For Critical Microsoft Word RCE Bug

There has been a proof-of-concept published recently for CVE-2023-21716 that analyzes this vulnerability. This vulnerability has been marked as “Critical” and has been detected in Microsoft Word which permits remote code execution (RCE).

Microsoft’s latest Patch Tuesday release in February patched the vulnerability, preventing it from being exploited. In ‘wwlib.dll’ of Microsoft Office, this RCE flaw was initially discovered by a security analyst, Joshua Drake Last year.

The researcher notified Microsoft immediately of his discovery after sending a technical advisory containing a PoC demonstrating that the vulnerability can be exploited.

The vulnerability could potentially be exploited by a remote attacker to execute code on a compromised system.

Vulnerability Details

  • CVE ID: CVE-2023-21716
  • CVSS Score: 9.8
  • Severity: Critical
  • Flaw: Remote Code Execution (RCE)

A remote attacker could potentially take advantage of the issue to execute code. As a result, the attacker has the same permissions as the victim, who opened the malicious [.RTF] file with the same privileges.

A malicious file can be delivered to a victim by attaching it to an email, which is perhaps the easiest way to deliver it, but there are many other methods also available.

In an effort to prevent users from falling victim to this kind of attack, Microsoft warns that they do not have to open the malicious RTF document. The attacker can begin exploiting the system simply by loading a version of it in the Preview Pane.

According to the researcher’s findings, the RTF parser incorporated in Microsoft Word possesses a vulnerability to heap corruption. 

This vulnerability is activated when the software is handling a font table denoted by “\fonttbl” that consists of a considerable number of fonts marked by “\f###.”

An attacker could use a properly crafted heap layout to exploit the bug for arbitrary code execution after memory corruption occurs. To demonstrate code execution, the PoC does not launch the Calculator app in Windows to illustrate heap corruption.

The vulnerability does not appear to be exploited in the wild at the present time. At the present time, Microsoft believes that exploiting the issue is unlikely to occur.


There is a fix provided by Microsoft for users that are not able to apply the fix. As Microsoft recommends users to read emails in plain text format. However, this fix is unlikely to be adopted since there will be no enhancements or improvements to the user experience.

There is also a workaround that can be used to make sure RTF documents don’t open when they’re from untrusted or unknown sources by enabling the Microsoft Office File Block policy.

In addition to requiring modification of the Windows Registry, this method also comes with some risks. However, there is no doubt that the best way to address this vulnerability is to install a Microsoft security update.

Network Security Checklist – Download Free E-Book


Latest articles

Researchers Exploited Nexus Repository Using Directory Traversal Vulnerability

Hackers target and exploit GitHub repositories for a multitude of reasons and illicit purposes.The...

DDNS Service In Fortinet Or QNAP Embedded Devices Exposes Sensitive Data, Researchers Warn

Hackers employ DNS for various purposes like redirecting traffic to enable man-in-the-middle attacks, infecting...

PoC Exploit Released For macOS Privilege Escalation Vulnerability

A new vulnerability has been discovered in macOS Sonoma that is associated with privilege...

CatDDoS Exploiting 80+ Vulnerabilities, Attacking 300+ Targets Daily

Malicious traffic floods targeted systems, servers, or networks in Distributed Denial of Service (DDoS)...

GNOME Remote Desktop Vulnerability Let Attackers Read Login Credentials

GNOME desktop manager was equipped with a new feature which allowed remote users to...

Kesakode: A Remote Hash Lookup Service To Identify Malware Samples

Today marks a significant milestone for Malcat users with the release of version 0.9.6,...

Cisco Firepower Vulnerability Let Attackers Launch SQL Injection Attacks

 A critical vulnerability has been identified in Cisco Firepower Management Center (FMC) Software's web-based...
Guru baran
Guru baran
Gurubaran is a co-founder of Cyber Security News and GBHackers On Security. He has 10+ years of experience as a Security Consultant, Editor, and Analyst in cybersecurity, technology, and communications.

Free Webinar

Live API Attack Simulation

94% of organizations experience security problems in production APIs, and one in five suffers a data breach. As a result, cyber-attacks on APIs increased from 35% in 2022 to 46% in 2023, and this trend continues to rise.
Key takeaways include:

  • An exploit of OWASP API Top 10 vulnerability
  • A brute force ATO (Account Takeover) attack on API
  • A DDoS attack on an API
  • Positive security model automation to prevent API attacks

Related Articles