CVE-2019-16992 in App
Summary
by MITRE
The Keybase app 2.13.2 for iOS provides potentially insufficient notice that it is employing a user's private key to sign a certain cryptocurrency attestation (that an address at keybase.io can be used for Stellar payments to the user), which might be incompatible with a user's personal position on the semantics of an attestation.
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Analysis
by VulDB Data Team • 12/28/2023
The vulnerability described in CVE-2019-16992 represents a significant issue in the Keybase iOS application version 2.13.2 concerning cryptographic attestation practices and user consent mechanisms. This flaw specifically pertains to how the application handles the signing of cryptocurrency attestations, particularly those related to Stellar payments, where the app utilizes a user's private key without providing adequate warning about this specific action. The core problem lies in the insufficient disclosure of the attestation process, creating a potential mismatch between user expectations and the actual cryptographic operations being performed. This vulnerability operates at the intersection of user experience design and cryptographic security, where the lack of clear communication about private key usage creates confusion and potential security risks for users who may not fully understand the implications of signing cryptocurrency attestations. The issue directly relates to CWE-668, which addresses insufficient warning about dangerous features, and also connects to CWE-312, concerning exposure of sensitive information through side channels.
The technical implementation flaw involves the application's attestation workflow where users are not properly informed that their private key will be used to sign a specific cryptocurrency attestation related to Stellar payment addresses. When a user attempts to verify their Stellar payment address through Keybase, the application automatically employs the user's private key to create a cryptographic signature without providing clear notice of this specific action. This process bypasses proper user consent mechanisms and creates a situation where users may unknowingly authorize the use of their private key for cryptocurrency-related attestations. The vulnerability is particularly concerning because cryptocurrency attestations can have long-term implications for user accounts and financial security, yet the application fails to provide adequate context about the nature and scope of the signing operation. The flaw also relates to ATT&CK technique T1552.001, which covers credentials from password stores, as the private key usage could potentially expose credential material in unexpected contexts.
The operational impact of this vulnerability extends beyond simple user confusion to potentially compromise cryptographic security practices within the Keybase ecosystem. Users who are not properly warned about the use of their private keys for cryptocurrency attestations may inadvertently create signatures that could be misused or misunderstood in financial contexts. This situation creates a risk of user error where individuals may sign attestations without understanding the full implications of their cryptographic actions, potentially leading to security misconfigurations or unauthorized financial attestations. The vulnerability also undermines user trust in the application's security model, as the lack of clear communication about private key usage violates fundamental principles of secure user interface design. Additionally, this issue could be exploited in social engineering scenarios where malicious actors might attempt to manipulate users into signing cryptocurrency attestations without proper understanding of the consequences, making it a significant concern for both individual users and the broader cryptocurrency community that relies on proper attestation practices.
Mitigation strategies for this vulnerability should focus on improving user interface design and consent mechanisms within the Keybase application. The most effective approach involves implementing clear, explicit warnings before any private key usage occurs, particularly for cryptocurrency-related operations. Users should receive detailed notifications explaining exactly what they are signing, the cryptographic implications, and the specific cryptocurrency context of the attestation. The application should provide users with the ability to review and confirm the exact content of the attestation before signing, ensuring that cryptographic operations are performed only with explicit user consent. Organizations implementing similar cryptographic attestation systems should adopt security standards such as those outlined in NIST SP 800-57 for cryptographic key management and ensure that user interfaces provide adequate security context. The solution should also incorporate proper logging and monitoring of attestation operations to detect and prevent unauthorized or unexpected signing activities, while maintaining compliance with industry best practices for cryptographic security and user consent as specified in various security frameworks and guidelines.