CyberSecBulletin
CVE-2023-43636NVD status: Modified

EVE OS: Insufficient Verification of Data Authenticity

Published Updated By the CyberSecBulletin desk

CVE-2023-43636 is a high-severity insufficient verification of data authenticity vulnerability in EVE OS from LF-Edge, Zededa, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 9.5.0, 8.6.0 as the first without the flaw, so updating EVE OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update EVE OS to 9.5.0 or 8.6.0, whichever matches your release line, or a later version.
  2. Update Edge Virtualization Engine to 8.6.0 or 9.5.0, whichever matches your release line, or a later version.
  3. Read the advisory on asrg.io for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
LF-Edge, ZededaEVE OS9.0.0 up to, but not including, 9.5.0; before 8.6.09.5.0, 8.6.0
Linux FoundationEdge Virtualization Enginebefore 8.6.0; 9.0.0 up to, but not including, 9.5.08.6.0, 9.5.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA (asrg.io)
CVSS 3.18.8HighNVD

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Insufficient Verification of Data Authenticity

The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

More Insufficient Verification of Data Authenticity vulnerabilities (CWE-345)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in EVE OS

All EVE OS vulnerabilities

Recent Insufficient Verification of Data Authenticity vulnerabilities

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