CVE-2020-1905 in WhatsApp
Summary
by MITRE • 10/06/2020
Media ContentProvider URIs used for opening attachments in other apps were generated sequentially prior to WhatsApp for Android v2.20.185, which could have allowed a malicious third party app chosen to open the file to guess the URIs for previously opened attachments until the opener app is terminated.
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Analysis
by VulDB Data Team • 11/17/2020
The vulnerability described in CVE-2020-1905 represents a significant security flaw in WhatsApp for Android that stems from predictable URI generation within the Media ContentProvider component. This issue affects versions prior to v2.20.185 and exposes users to potential unauthorized access to their media attachments through a well-known attack pattern involving sequential URI guessing. The vulnerability operates at the application-level within the Android operating system's security model, specifically targeting how WhatsApp handles file sharing and URI generation for media content.
The technical flaw manifests in the sequential generation of ContentProvider URIs used to reference media attachments when sharing files with other applications. This predictable pattern allows malicious third-party applications that are chosen to open files to systematically guess the URIs of previously opened attachments. The vulnerability is particularly concerning because it leverages the inherent trust relationship between applications in Android's security architecture, where one application can request another to open a file. When an application generates URIs sequentially without proper randomization or entropy, it creates a predictable attack surface that can be exploited by adversaries with minimal computational resources.
The operational impact of this vulnerability extends beyond simple data exposure to potentially enable more sophisticated attacks within the Android ecosystem. An attacker with a malicious application installed on the same device could monitor the ContentProvider URI generation patterns and use this information to access previously shared media files, including photos, videos, and documents. This creates a persistent threat vector that remains active throughout the session until the target application is terminated, allowing for extended periods of unauthorized access. The vulnerability is particularly dangerous in environments where users frequently share sensitive media content through WhatsApp, as it could expose personal communications, business documents, or other confidential materials.
This vulnerability aligns with CWE-200, which describes "Information Exposure," and demonstrates how predictable identifiers can lead to unauthorized information access. The issue also relates to ATT&CK technique T1059, which covers "Command and Scripting Interpreter," as the predictable URI patterns could be exploited through automated scripts that systematically attempt to access content. From a security architecture perspective, this represents a failure in proper entropy implementation and identifier generation practices, violating fundamental principles of secure application design. The vulnerability highlights the importance of implementing cryptographically secure random number generation and proper URI management in mobile applications that handle user data.
Mitigation strategies for this vulnerability require both immediate application-level fixes and broader security awareness measures. WhatsApp addressed this issue by implementing randomized URI generation in version 2.20.185, which ensures that each ContentProvider URI is generated with sufficient entropy to prevent sequential guessing attacks. Users should maintain updated versions of WhatsApp and other messaging applications to ensure they benefit from the latest security patches. Additionally, security-conscious organizations should implement mobile device management policies that enforce application updates and monitor for potentially malicious applications that might attempt to exploit similar vulnerabilities. Network administrators should also consider implementing monitoring solutions that can detect unusual patterns of URI access attempts that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper identifier management and entropy implementation in mobile security architectures, particularly in applications that handle sensitive user data.