CVE-2020-24722

low-risk
Published 2020-10-07

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.

Do I need to act?

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0.32% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.9/10 Medium
NETWORK / HIGH complexity

Affected Products (2)

Exposure Notifications
Exposure Notifications

Affected Vendors

Exposure Notifications Project

References (8)

Exploit http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymizati...
Exploit http://seclists.org/fulldisclosure/2020/Oct/12
Third Party Advisory https://blog.google/inside-google/company-announcements/update-exposure-notifica...
Third Party Advisory https://github.com/google/exposure-notifications-internals/blob/main/en-risks-an...
Exploit http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymizati...
Exploit http://seclists.org/fulldisclosure/2020/Oct/12
Third Party Advisory https://blog.google/inside-google/company-announcements/update-exposure-notifica...
Third Party Advisory https://github.com/google/exposure-notifications-internals/blob/main/en-risks-an...
26
/ 100
low-risk
Severity 18/34 · Moderate
Exploitability 1/34 · Minimal
Exposure 7/34 · Low