Himmelblau offline auth permits authentication with invalid Hello PIN
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 0.9.17
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. A vulnerability present in versions 0.9.10 through 0.9.16 allows a user to authenticate to a Linux host via Himmelblau using an invalid Linux Hello PIN, provided the host is offline. While the user gains access to the local system, Single Sign-On (SSO) fails due to the network being down and the inability to issue tokens (due to a failure to unlock the Hello key). The core issue lies in an incorrect assumption within the `acquire_token_by_hello_for_business_key` function: it was expected to return a `TPMFail` error for an invalid Hello key when offline, but instead, a preceding nonce request resulted in a `RequestFailed` error, leading the system to erroneously transition to an offline success state without validating the Hello key unlock. This impacts systems using Himmelblau for authentication when operating in an offline state with Hello PIN authentication enabled. Rocky Linux 8 (and variants) are not affected by this vulnerability. The problem is resolved in Himmelblau version 0.9.17. A workaround is available for users who cannot immediately upgrade. Disabling Hello PIN authentication by setting `enable_hello = false` in `/etc/himmelblau/himmelblau.conf` will mitigate the vulnerability.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- himmelblau-idm himmelblau
From 0.9.10 · fixed in 0.9.17