CVE-2024-38112

Windows MSHTML Platform Spoofing Vulnerability

Recent assessments:

remmons-r7 at July 19, 2024 2:51pm UTC reported:

Trend Micro reported this vulnerability to Microsoft after observing Void Banshee APT exploitation in the wild; the zero-day attack hinged on the premise that MHTML links would automatically open in the old Internet Explorer engine. Within the old engine context, HTA files will prompt to open by default, facilitating easier code execution. The threat actors were observed appending many spaces to the file name to misrepresent the secondary HTA file as a PDF in the IE pop-up box. Additionally, Check Point researcher Haifei Li is credited for a report that resulted in a “Defense-in-depth” patch for this chain, which is probably related to the HTA file name misrepresentation trick.

The process of exploitation would typically look like this:

• An attacker site is visited or a phishing message is sent to the victim.

• The victim downloads a malicious “.url” file that masquerades as a legitimate document.

• The victim clicks the “.url” payload, opening the embedded “mhtml:” link and launching Internet Explorer.

• The IE engine prompts the user to open the second-stage HTA file.

• The victim clicks “open” on the pseudo-PDF prompt.

• The victim clicks “Allow” on the IE security prompt for the “HTML Application host” execution.

In summary, the intent of this attack chain is to misrepresent and remove some security hurdles for malware execution on Windows. Successful exploitation does still require quite a bit of clicking through prompts by the user. However, this is likely enough to significantly increase execution numbers for the affiliated malware campaign, which was reported to be deploying information stealers.

Assessed Attacker Value: 3
Assessed Attacker Value: 3Assessed Attacker Value: 2