Google Threat Analysis Group researchers discovered the zero-day vulnerability in late October 2022, it was exploited by APT37 using specially crafted documents.
The attackers attempted to capitalize on the recent Itaewon Halloween crowd crush to trick users into opening the weaponized document and infecting their systems.
“These malicious documents exploited an Internet Explorer 0-day vulnerability in the JScript engine, CVE-2022-41128. Our policy is to quickly report vulnerabilities to vendors, and within a few hours of discovering this 0-day, we reported it to Microsoft and patches were released to protect users from these attacks.” reads the post published by TAG.
The document downloaded a rich text file (RTF) template from a remote server, which in turn fetched remote HTML content. Experts pointed out that Office renders this HTML content using Internet Explorer (IE). Using this technique the attackers are able to trigger IE zero-day using weaponized Office documents since 2017 (e.g. CVE-2017-0199).
TAG determined that the APT group abused the zero-day vulnerability in the JScript engine of Internet Explorer.
TAG also identified other documents that were used to exploit the same vulnerability, the experts speculate they may be part of the same campaign.
TAG reported the vulnerability to Microsoft on October 31, 2022, the IT giant addressed it on November 8, 2022.
Google TAG shared indicators of compromise (IOCs) for this campaign.
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(SecurityAffairs – hacking, Internet Explorer)