8.8 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
6.7 Medium
AI Score
Confidence
Low
4.3 Medium
CVSS2
Access Vector
LOCAL
Access Complexity
LOW
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:S/C:P/I:P/A:P
0.0004 Low
EPSS
Percentile
8.7%
In EVE OS, the “measured boot” mechanism prevents a compromised device from accessing
the encrypted data located in the vault.
As per the “measured boot” design, the PCR values calculated at different stages of the boot
process will change if any of their respective parts are changed.
This includes, among other things, the configuration of the bios, grub, the kernel cmdline,
initrd, and more.
However, this mechanism does not validate the entire rootfs, so an attacker can edit the
filesystem and gain control over the system.
As the default filesystem used by EVE OS is squashfs, this is somewhat harder than an ext4,
which is easily changeable.
This will not stop an attacker, as an attacker can repackage the squashfs with their changes
in it and replace the partition altogether.
This can also be done directly on the device, as the “003-storage-init” container contains the
“mksquashfs” and “unsquashfs” binaries (with the corresponding libs).
An attacker can gain full control over the device without changing the PCR values, thus 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.
8.8 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
6.7 Medium
AI Score
Confidence
Low
4.3 Medium
CVSS2
Access Vector
LOCAL
Access Complexity
LOW
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:S/C:P/I:P/A:P
0.0004 Low
EPSS
Percentile
8.7%