CyberSecBulletin
CVE-2022-48251NVD status: Modified

Cortex-a53 Firmware: Observable Discrepancy

Published Updated By the CyberSecBulletin desk

CVE-2022-48251 is a high-severity observable discrepancy vulnerability in Cortex-a53 Firmware from Arm, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.88% chance of exploitation within 30 days, higher than 60% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Cortex-a53 Firmware you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
ArmCortex-a53 FirmwareNot specified in the recordNot stated
ArmCortex-a55 FirmwareNot specified in the recordNot stated
ArmCortex-a57 FirmwareNot specified in the recordNot stated
ArmCortex-a72 FirmwareNot specified in the recordNot stated
ArmCortex-a73 FirmwareNot specified in the recordNot stated
ArmCortex-a75 FirmwareNot specified in the recordNot stated
ArmCortex-a76 FirmwareNot specified in the recordNot stated
ArmCortex-a76ae FirmwareNot specified in the recordNot stated
ArmCortex-a77 FirmwareNot specified in the recordNot stated
ArmCortex-a78 FirmwareNot specified in the recordNot stated

Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
NoneAvailability is not affected.

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

Official description

The AES instructions on the ARMv8 platform do not have an algorithm that is "intrinsically resistant" to side-channel attacks. NOTE: the vendor reportedly offers the position "while power side channel attacks ... are possible, they are not directly caused by or related to the Arm architecture."

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

The underlying weakness: Observable Discrepancy

The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.

How developers prevent this class of flaw

  • Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

More Observable Discrepancy vulnerabilities (CWE-203)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Recent Observable Discrepancy vulnerabilities

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