CVE-2018-12271 in App
Summary
by MITRE
** DISPUTED ** An issue was discovered in the com.getdropbox.Dropbox app 100.2 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 • 06/18/2024
The vulnerability identified as CVE-2018-12271 represents a critical security flaw in the Dropbox iOS application version 100.2 that undermines the intended biometric authentication mechanism. This issue specifically affects the implementation of TouchID validation through the LAContext class, which is designed to provide secure user authentication through biometric means. The flaw stems from the application's failure to properly implement security controls that would normally prevent unauthorized access when biometric authentication is compromised or manipulated.
The technical root cause of this vulnerability lies in the improper handling of the LAContext return Boolean value during biometric authentication processes. The implementation does not utilize the kSecAccessControlUserPresence protection mechanism that would normally require explicit user presence verification before granting authentication access. This omission creates a scenario where an attacker can manipulate the authentication flow by overriding the Boolean return value to always be true, effectively bypassing the intended security controls. The vulnerability essentially allows for arbitrary fingerprint authentication without proper validation, fundamentally undermining the security model that TouchID is designed to provide.
From an operational impact perspective, this vulnerability creates a significant risk for users who rely on biometric authentication for accessing their Dropbox accounts. The attack vector is particularly concerning as it does not require physical access to the device or sophisticated technical skills beyond basic manipulation of the application's authentication flow. The implications extend beyond simple unauthorized access to potentially exposing sensitive data stored in cloud environments, especially when considering that Dropbox serves as a platform for storing various types of personal and business information. This vulnerability could enable attackers to gain access to documents, photos, and other confidential materials that users expect to be protected through secure authentication mechanisms.
The security implications of this vulnerability align with CWE-312 (Sensitive Data Exposure) and CWE-311 (Missing Encryption of Sensitive Data) categories, as the flaw directly impacts the secure handling of biometric authentication data and user credentials. The vulnerability also maps to ATT&CK technique T1550.002 (Use of Authenticated Sessions) and T1078.004 (Valid Accounts) as it exploits legitimate authentication mechanisms to gain unauthorized access. The vendor's assessment that this is not an attack of interest within their threat model, particularly excluding jailbroken devices, suggests a limited recognition of the broader security implications. However, this assessment may be overly restrictive as the vulnerability could potentially be exploited through various means including social engineering, physical access attacks, or by leveraging other application flaws that could lead to privilege escalation.
Mitigation strategies for this vulnerability should include immediate application updates from the vendor to properly implement the kSecAccessControlUserPresence protection mechanism and ensure that biometric authentication returns are properly validated. Organizations should also implement additional security controls such as multi-factor authentication, regular security assessments of mobile applications, and user education about the importance of keeping applications updated. The implementation of proper access control mechanisms and regular security testing of authentication flows would help prevent similar issues in other applications that rely on biometric authentication. Additionally, system administrators should consider implementing monitoring solutions that can detect unusual authentication patterns that might indicate exploitation attempts.