Attacker Value
Very High
(1 user assessed)
Exploitability
Very High
(1 user assessed)
User Interaction
None
Privileges Required
None
Attack Vector
Network
2

CVE-2020-35665

Disclosure Date: December 23, 2020 •
CVE-2020-35665 CVSS v3 Base Score: 9.8
Exploited in the Wild
Reported by h00die-gr3y
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Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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.

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1
Ratings
  • Attacker Value
    Very High
  • Exploitability
    Very High
Common in enterpriseEasy to weaponizeGives privileged accessUnauthenticatedVulnerable in default configuration
Technical Analysis

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.
Ransomeware.

References

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

Credits

IHTeam

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CVSS V3 Severity and Metrics
Base Score:
9.8 Critical
Impact Score:
5.9
Exploitability Score:
3.9
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
None
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
n/a
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • terra-master

Products

  • terramaster operating system

Exploited in the Wild

Reported by:

Additional Info

Authenticated
Unknown
Exploitable
Unknown
Reliability
Unknown
Stability
Unknown
Available Mitigations
Unknown
Shelf Life
Unknown
Userbase/Installbase
Unknown
Patch Effectiveness
Unknown
Technical Analysis