Vulnerability in Exposure Notifications Project
CVE-2020-24722
An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications) protocol through 2020-10-05, as used in COVID-19 applications on Android and iOS. The encrypted metadata block with a TX value lacks a checksum, allowing bitflipping to amplify a contamination attack. This can cause metadata deanonymization and risk-score inflation. NOTE: the vendor's position is "We do not believe that TX power authentication would be a useful defense against relay attacks.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.025 (83.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 84th percentile — 83.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.025 · newest: 0.025 · change: 0.000
Affected products
Weakness classification (CWE)
References
- blog.google/inside-google/company-announcements/update-exposure-notifications (Third Party Advisory)
- seclists.org/fulldisclosure/2020/Oct/12 (Exploit, Mailing List, Third Party Advisory)
- github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitig… (Third Party Advisory)
- packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Ris… (Exploit, VDB Entry, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-24722?
- CVE-2020-24722 is a medium-severity vulnerability in Exposure Notifications Project, classified under Authentication Bypass by Capture-replay. CVSS score: 5.9/10. Published 2020-10-07.
- How severe is CVE-2020-24722?
- Medium severity. CVSS v3 base score is 5.9 out of 10.