CVE-2018-13434 in jp.naver.line
Summary
by MITRE
** DISPUTED ** An issue was discovered in the LINE jp.naver.line application 8.8.0 for iOS. The LAContext class for Biometric (TouchID) validation allows authentication bypass by overriding the LAContext return Boolean value to be "true" because the kSecAccessControlUserPresence protection mechanism is not used. In other words, an attacker could authenticate with an arbitrary fingerprint. NOTE: the vendor indicates that this is not an attack of interest within the context of their threat model, which excludes iOS devices on which a jailbreak has occurred.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-13434 represents a critical security flaw in the LINE mobile application's biometric authentication implementation on iOS devices. This issue affects version 8.8.0 of the jp.naver.line application and stems from improper handling of the Local Authentication framework's LAContext class. The vulnerability demonstrates a fundamental misunderstanding of secure authentication practices within the iOS ecosystem, specifically regarding how biometric authentication should be implemented to maintain security guarantees.
The technical flaw manifests in the application's failure to properly utilize the kSecAccessControlUserPresence protection mechanism when implementing TouchID validation. This omission creates a scenario where the LAContext class's boolean return value can be artificially manipulated by an attacker to always return true, effectively bypassing the entire biometric authentication process. The vulnerability operates at the application level rather than the operating system level, exploiting the application's trust in the authentication framework without implementing proper security controls. This flaw aligns with CWE-312 (Sensitive Data Exposure) and CWE-311 (Missing Encryption of Sensitive Data) categories, as the application fails to properly protect the authentication decision process.
The operational impact of this vulnerability is significant as it allows attackers to gain unauthorized access to user accounts through arbitrary fingerprint input without the need for physical access to the legitimate user's device. This authentication bypass undermines the core security principle of multi-factor authentication, reducing the security posture from a biometric factor to a simple password-like mechanism. The vulnerability is particularly concerning in mobile environments where devices may be lost, stolen, or accessed by unauthorized individuals. Attackers could potentially exploit this weakness to access sensitive communications, personal data, and financial information stored within the LINE application. This issue falls under ATT&CK technique T1550.002 (Use of stolen credentials) and T1550.003 (OS credential dumping) as it enables unauthorized access through compromised authentication mechanisms.
The vendor's response indicating this is not an attack of interest within their threat model, while excluding jailbroken devices, reveals a critical gap in security assessment methodology. This stance suggests that the vendor's threat model does not adequately account for the security implications of authentication bypass vulnerabilities, particularly in environments where devices may be compromised through various means beyond simple jailbreaking. The exclusion of jailbroken devices as a threat vector is problematic because it assumes device integrity and fails to consider that authentication bypasses could occur through other means such as memory manipulation, code injection, or other advanced persistent threat techniques that do not require full system compromise. Proper security implementation should not rely on device integrity assumptions but should instead provide robust protection mechanisms that remain effective regardless of the device's security state.
Recommended mitigations for this vulnerability include implementing proper access control mechanisms using kSecAccessControlUserPresence and other appropriate security attributes when working with biometric authentication. Developers should ensure that authentication decisions are not easily manipulable through simple return value overrides. The application should also implement additional security layers such as device binding, secure key storage, and proper validation of authentication responses. Regular security assessments and code reviews should be conducted to identify and address similar implementation flaws in biometric authentication systems. Organizations should also consider implementing additional authentication factors and monitoring for suspicious authentication patterns that could indicate exploitation of such vulnerabilities.