Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2023-43633

Disclosure Date: September 21, 2023
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

On boot, the Pillar eve container checks for the existence and content of
“/config/GlobalConfig/global.json”.

If the file exists, it overrides the existing configuration on the device on boot.

This allows an attacker to change the system’s configuration, which also includes some
debug functions.

This could be used to unlock the ssh with custom “authorized_keys” via the
“debug.enable.ssh” key, similar to the “authorized_keys” finding that was noted before.

Other usages include unlocking the usb to enable the keyboard via the “debug.enable.usb”
key, allowing VNC access via the “app.allow.vnc” key, and more.

An attacker could easily enable these debug functionalities without triggering the “measured
boot” mechanism implemented by EVE OS, and without marking the device as “UUD”
(“Unknown Update Detected”).
This is because the “/config” partition is not protected by “measured boot”, it is mutable and it
is not encrypted in any way.

An attacker can gain full control over the device without changing the PCR values, thereby not
triggering the “measured boot” mechanism, and having full access to the vault.

Note:

This issue was partially fixed in these commits (after disclosure to Zededa), where the config
partition measurement was added to PCR13:

• aa3501d6c57206ced222c33aea15a9169d629141

• 5fef4d92e75838cc78010edaed5247dfbdae1889.

This issue was made viable in version 9.0.0 when the calculation was moved to PCR14 but it was not included in the measured boot.

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CVSS V3 Severity and Metrics
Base Score:
8.8 High
Impact Score:
6
Exploitability Score:
2
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Changed
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

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Additional Info

Technical Analysis