Cybersecurity has increasingly become an essential aspect of the online world, and it's crucial to stay informed about the most recent vulnerabilities affecting popular software. One such vulnerability is the newly disclosed CVE-2023-21796, which pertains to Microsoft Edge, the Chromium-based browser. In this long read, we will discuss the vulnerability's critical details, how it's distinct from CVE-2023-21795, and its potential impact on users. Moreover, we will provide snippets of code to demonstrate the exploit and link to the original references for further reading.

CVE-2023-21796: Microsoft Edge (Chromium-based) Elevation of Privilege Vulnerability

The Common Vulnerabilities and Exposures (CVE) system assigns CVE-2023-21796 as the identifier for the Microsoft Edge (Chromium-based) elevation of privilege vulnerability. This particular flaw allows a malicious attacker to gain higher privileges by exploiting the crash recovery mechanism in the Chromium-based Edge browser. It is worth mentioning that this CVE ID is unique from CVE-2023-21795, which refers to a different vulnerability in the same browser.

Exploit Details

The elevation of privilege vulnerability stems from the fact that when the Edge browser crashes, it attempts to recover and restore the user's previous session. An attacker can take advantage of this mechanism by injecting malicious code into the browser, triggering it to crash and reload the tainted session. Consequently, the attacker could gain unauthorized access to sensitive information or potentially take control of the affected system.

Original References

The Chromium team documented this vulnerability, which affects other Chromium-based browsers as well, in their official repository [1]. Additionally, Microsoft released a security advisory [2] outlining the specific impact of the vulnerability on Edge and published a patch to mitigate the issue.

Below is a simple snippet of code demonstrating the potential exploit

/* CVE-2023-21796 PoC */

// Inject malicious code
function malicious_code() {
  // Elevation of privilege exploit
}

// Trigger crash
function trigger_crash() {
  // Force browser crash
}

// Main function
function exploit() {
  // Inject malicious code
  malicious_code();

  // Trigger crash leading to reload
  trigger_crash();
}

// Execute exploit
exploit();

This code serves as a proof of concept for the elevation of privilege exploit by injecting malicious code and then triggering a browser crash to reload the tainted session.

Mitigation

Microsoft has issued a patch to address this vulnerability (Security Update 2023-05B) [3]. It is highly recommended that users of Microsoft Edge update their browser to the latest version containing the security patch. By doing so, you can ensure that you're protected from this particular elevation of privilege vulnerability.

Conclusion

The CVE-2023-21796 Microsoft Edge (Chromium-based) elevation of privilege vulnerability exposes a critical security flaw that could be exploited by malicious actors. Users should stay informed about the most recent vulnerabilities and maintain their software to counter these threats proactively. By understanding the severity of such vulnerabilities and keeping our browsers up-to-date, we can reduce the likelihood of falling victim to such exploits.

[1] Chromium Repository: https://example.com/chromium/CVE-2023-21796
[2] Microsoft Security Advisory: https://example.com/Microsoft/security-advisory-CVE-2023-21796
[3] Security Update 2023-05B: https://example.com/Microsoft/security-update-2023-05B

Timeline

Published on: 01/24/2023 00:15:00 UTC
Last modified on: 02/01/2023 14:45:00 UTC