On February 4th, 2021, two separate zero-day vulnerabilities impacting the Chrome and Internet Explorer web browsers were announced.
Google confirmed a high severity vulnerability in Google Chrome that is tracked as CVE-2021-21148. The vulnerability is classified as Heap Buffer Overflow. While Google has stated there are reports of exploitation in the wild, no additional details have been provided at this time.
The South Korean cyber-security company ENKI confirmed the existence of a zero-day vulnerability affecting Internet Explorer 11, after they identified targeted attacks against their employees. The currently unnamed IE vulnerability is classified as a double-free vulnerability and has been exploited to exfiltrate victim information and deliver additional malicious content.
What we’re doing about it
- MVS has local plugins to identify systems vulnerable to CVE-2021-21148
- MVS will automatically add the relevant checks for the Internet Explorer zero-day vulnerability once details are made available
- MVS customers seeking assistance with their review or scans, please contact your MVS consultant or the eSentire Security Operations Center (SOC)
- eSentire security teams continue to track this topic for additional details and detection opportunities
What you should do about it
- Ensure Chrome browsers are updated to version 88.0.4324.150
- Consider replacing Internet Explorer with alternative modern browsers such as Microsoft Edge, Mozilla Firefox, or Google Chrome
- Support for Internet Explorer is set to end on August 17th, 2021
There is speculation that CVE-2021-21148 was exploited in this campaign. Links between exploitation of CVE-2021-21148 and this campaign have not been verified at this time.