Microsoft responds to a recent security advisory from Autodesk by publishing an out-of-band advisory for Office products integrating the Autodesk library.
Background
On April 15, Autodesk released a security advisory, ADSK-SA-2020-0002, to address six vulnerabilities in the Autodesk Filmbox (FBX) Software Development Kit, which “allows application and content vendors to transfer existing content into the FBX format with minimal effort.”
In response to Autodesk’s advisory, Microsoft issued an out-of-band advisory, ADV200004, on April 21, as the FBX library is integrated into specific versions of Microsoft Office, Office 365 ProPlus and Paint 3D.
Analysis
In ADSK-SA-2020-0002, Autodesk patched the following six vulnerabilities:
| CVE | Vulnerability | Impact | CVSSv3.x* |
|---|---|---|---|
| CVE-2020-7080 | Buffer Overflow | Arbitrary Code Execution | 7.8 |
| CVE-2020-7081 | Type Confusion | Arbitrary Code Execution, Denial of Service | N/A |
| CVE-2020-7082 | Use-After-Free | Arbitrary Code Execution | N/A |
| CVE-2020-7083 | Integer Overflow | Denial of Service | N/A |
| CVE-2020-7084 | Null Pointer Dereference | Denial of Service | 5.5 |
| CVE-2020-7085 | Heap Overflow | Arbitrary Code Execution | 7.8 |
*Please note that the CVSSv3.x scores referenced in the table above were available at the time this blog post was published and may be subject to change.
Though not all the vulnerabilities had CVSSv3.x scores assigned in their U.S. National Vulnerability Database entries, Autodesk collectively rated their advisory as High.
Exploitation of these vulnerabilities requires an attacker to convince their victim to open a malicious Microsoft Office, Office 365 ProPlus or Paint 3D file that contains specially crafted 3D content which takes advantage of the vulnerabilities in the FBX library.
Proof of concept
F-Secure researcher Max Van Amerongen, credited with the discovery of CVE-2020-7085, has tweeted a proof-of-concept video demonstrating the heap overflow vulnerability:
My Autodesk FBX Heap Overflow (CVE-2020-7085) has now been disclosed at https://t.co/jvumWcCZE7
— maxpl0it (@maxpl0it) April 17, 2020
Works on FBX SDK < 2019.5
PoC video from disclosure: pic.twitter.com/vayCIomgaP
Solution
Microsoft’s advisory states that it has addressed these vulnerabilities in the following products:
| Product | Version | Knowledge Base Article |
|---|---|---|
| Microsoft Office 2016 | Click-to-Run 32-bit and 64-bit editions | Office 2016 C2R |
| Microsoft Office 2019 | 32-bit and 64-bit editions | Office 2019 |
| Office 365 ProPlus | 32-bit and 64-bit editions | Office 365 ProPlus |
| Paint 3D | Paint 3D Release Notes |
However, at the time this blog post was published, there were no new updates to the articles listed above. The last time these articles were updated was on April 14, which coincided with April’s Patch Tuesday release. It is unclear if Microsoft plans to release its updates as part of this out-of-band release, or if the fixes will be included as part of May’s Patch Tuesday release.
Since FBX is an included library in these versions of Office and Paint 3D and Microsoft released an out-of-band advisory for these flaws, we strongly encourage organizations to apply these patches as soon as they are available.
Identifying affected systems
A list of Tenable plugins to identify these vulnerabilities will appear here as they’re released.
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