CVE-2023-43636
HIGHIn 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…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
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.
Affected Products
edge virtualization enginelinuxfoundationDetection & mitigation playbook
Vendor / applianceDetect
Inventory every linuxfoundation edge virtualization engine deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the linuxfoundation edge virtualization engine security patch or hotfix for CVE-2023-43636 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2023-43636 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2023-43636. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-43636 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2023-43636 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.