Oviva epa4all-client
IDP Discovery Document Signature Bypass
The client does not verify the signature on the central IDP's OpenID discovery document. An attacker who can man-in-the-middle the TLS connection to the identity provider can substitute a forged document that redirects the uri_puk_idp_enc and uri_puk_idp_sig endpoints to attacker-controlled URLs, capturing the SMC-B-signed authentication material.
This advisory contains limited information during coordinated disclosure. Please check back later for full details.
Description
Per Oviva's advisory, an attacker who can MITM the TLS connection between the client and the IDP — inside the Telematikinfrastruktur network — can substitute a forged discovery document. The forged document redirects uri_puk_idp_enc and uri_puk_idp_sig to attacker-controlled URLs. The client then encrypts the SMC-B-signed challenge response to the attacker's encryption key and POSTs it to the attacker's authentication endpoint, capturing the signed authentication material.
Impact
- An attacker positioned to MITM the TLS connection to the central IDP can capture the SMC-B-signed authentication response and the key material exchanged during login, compromising the confidentiality and integrity of the ePA authentication flow.
Mitigation
Update epa4all-client to 1.2.2 or later. No workaround is available for affected versions.
References
How We Can Help
Who We Are
The security researchers behind this advisory.
Dr. rer. nat. Simon Weber
Senior Pentester & MedSec Researcher
I evaluate your SaMD with the same industry-defining security insight I contributed to the BAK MV for the revision of the B3S standard.
- PhD on Hospital Cybersecurity
- Critical vulnerabilities found in hospital systems
- Alumni of THB MedSec Research Group
- gematik Security Hero
Dipl.-Inf. Volker Schönefeld
Senior Application Security Expert
As a former CTO and developer turned pentester, I work alongside your team to uncover vulnerabilities and find solutions that fit your architecture.
- 20+ years as CTO, 50M+ app downloads
- Architected and secured large-scale IoT fleets
- Certified Web Exploitation Specialist
- gematik Security Hero
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Machine Spirits specializes in security assessments for medical devices and healthcare IT. From MDR penetration testing to C5 cloud compliance, we help MedTech companies meet regulatory requirements.