CVE-2020-1908 in WhatsApp
Summary
by MITRE • 11/04/2020
Improper authorization of the Screen Lock feature in WhatsApp and WhatsApp Business for iOS prior to v2.20.100 could have permitted use of Siri to interact with the WhatsApp application even after the phone was locked.
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Analysis
by VulDB Data Team • 12/01/2020
The vulnerability identified as CVE-2020-1908 represents a critical authorization flaw in the Screen Lock feature implementation within WhatsApp and WhatsApp Business applications for iOS devices. This issue affected versions prior to v2.20.100 and exposed a significant security gap in the application's handling of device-level security controls. The flaw specifically pertained to how the messaging application managed its interaction with the iOS operating system's lock screen mechanisms, creating an unintended pathway for unauthorized access to application functionality.
The technical nature of this vulnerability stems from improper authorization controls that failed to adequately verify user authentication status when the device screen was locked. When a user locked their iOS device, the WhatsApp application should have enforced strict access controls preventing any interaction with its features until proper authentication was performed. However, the flaw allowed Siri commands to be processed and executed within the WhatsApp application context even when the device was secured, effectively bypassing the intended security boundaries. This misconfiguration created a scenario where voice-activated commands could trigger application functions without requiring the user to unlock their device first.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential data exposure and unauthorized communications. Attackers could leverage this flaw to access sensitive messaging conversations, send messages, and potentially interact with the application's features through Siri commands without physical access to the device or knowledge of the lock screen passcode. This represents a direct violation of the principle of least privilege and demonstrates a failure in implementing proper access control mechanisms at the application level. The vulnerability aligns with CWE-284, which addresses improper access control issues, and specifically relates to inadequate authorization controls that allow unauthorized access to application resources.
The security implications of this vulnerability are particularly concerning given WhatsApp's widespread use for sensitive communications and business transactions. The flaw essentially provided a backdoor mechanism that could be exploited by malicious actors to gain unauthorized access to personal and potentially confidential information. This type of vulnerability is categorized under the MITRE ATT&CK framework as a privilege escalation technique, specifically involving the exploitation of application-level security controls to bypass device-level protections. The issue highlights the importance of proper security testing and validation of application behavior in locked states, particularly for applications handling sensitive personal communications.
Mitigation strategies for this vulnerability required immediate updates to the affected WhatsApp applications, with version 2.20.100 implementing proper authorization checks for screen lock states. Users were advised to update their applications immediately to receive the security patch that corrected the authorization flow and ensured that Siri commands would not be processed when the device was locked. Organizations utilizing WhatsApp for business communications should have implemented additional monitoring to detect any unusual activity patterns that might indicate exploitation attempts. The vulnerability underscores the necessity for comprehensive security testing of applications in various device states and the critical importance of maintaining up-to-date security controls that properly enforce access restrictions based on authentication status.