CVE-2020-35665

An unauthenticated command-execution vulnerability exists in TerraMaster TOS through 4.2.06 via shell metacharacters in the Event parameter in include/makecvs.php during CSV creation.

Recent assessments:

h00die-gr3y at June 05, 2023 9:49am UTC reported:

Last two weeks, I spent some time on a TerraMaster F2-221 NAS server that I got from an old friend running TerraMaster Operating System (TOS) 4.x.
Research on the Internet shows that this server is full with vulnerabilities up to TOS 4.2.29. Surprisingly, no Metasploit modules were made to exploit these NAS servers and there are still plenty of vulnerable NAS servers connected to the Internet.

So I took the liberty to write three nice modules that exploits these NAS servers targeting different vulnerabilities.
This article is covering the first of three modules, called TerrorMaster 1 like we do with “good” movies released in the cinema. You can find the articles on TerrorMaster 2 here and TerrorMaster 3 here.

In December 2020, the IHTeam reported multiple vulnerabilities on TerraMaster NAS devices running TOS version 4.2.06 or lower.
You can read their analysis/advisory here.

TerrorMaster 1 is exploiting a vulnerability described in CVE-2020-35665 or CVE-2020-28188 that allows an unauthenticated attacker to create /upload a webshell via shell metacharacters in the Event parameter using the vulnerable endpoint include/makecvs.php during the CSV creation process.

You can find the module here in my local repository or as PR 18063 at the Metasploit Github development.

Mitigation

Please update your TOS version up to the latest supported TOS 4.2.x version or TOS 5.x version to be protected against all known vulnerabilities.
I strongly advice NOT to expose your TerraMaster NAS devices directly to the Internet, because you could end-up in a situation depicted below where your server has become a victim of ransomware.
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References

IHTeam advisory
TerrorMaster 1 – h00die-gr3y Metasploit local repository
TerrorMaster 1 – Metasploit PR 18063
TerrorMaster 2
TerrorMaster 3

Credits

IHTeam

Assessed Attacker Value: 5
Assessed Attacker Value: 5Assessed Attacker Value: 5