CVE-2020-1890 in WhatsApp
Summary
by MITRE
A URL validation issue in WhatsApp for Android prior to v2.20.11 and WhatsApp Business for Android prior to v2.20.2 could have caused the recipient of a sticker message containing deliberately malformed data to load an image from a sender-controlled URL without user interaction.
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Analysis
by VulDB Data Team • 11/12/2020
The vulnerability identified as CVE-2020-1890 represents a critical URL validation flaw within WhatsApp for Android applications that affected versions prior to v2.20.11 for standard WhatsApp and v2.20.2 for WhatsApp Business. This issue stemmed from insufficient input validation mechanisms that allowed malicious actors to craft specially formatted sticker messages containing malformed URLs. The flaw specifically targeted the image loading functionality within the messaging application's sticker handling mechanism, creating a pathway for unauthorized remote content retrieval.
The technical implementation of this vulnerability exploited a weakness in the application's URI parsing and validation logic. When a user received a sticker message containing a maliciously crafted URL, the application would automatically attempt to load the referenced image resource without requiring any user interaction or explicit consent. This automatic loading behavior occurred because the application failed to properly sanitize or validate the URL parameters embedded within the sticker data structure. The vulnerability essentially created a client-side code execution vector through image loading, as the application would fetch resources from arbitrary external servers controlled by the attacker.
From an operational security perspective, this vulnerability posed significant risks to end-user privacy and system integrity. The flaw could be exploited to deliver malicious payloads through seemingly benign sticker messages, potentially enabling attackers to perform reconnaissance activities such as tracking user interactions, delivering malware through image downloads, or conducting phishing attacks. The automatic nature of the URL loading meant that users could be compromised without any awareness of the attack, making it particularly dangerous for social engineering campaigns. This vulnerability directly impacts the principle of least privilege and user consent, as users were not given control over external resource loading decisions.
The attack surface for this vulnerability aligns with several ATT&CK framework techniques including T1190 (Exploit Public-Facing Application) and T1059 (Command and Scripting Interpreter) through the exploitation of client-side application flaws. From a CWE perspective, this vulnerability maps to CWE-20 (Improper Input Validation) and potentially CWE-94 (Improper Control of Generation of Code) when considering the potential for code execution through image loading mechanisms. The vulnerability also relates to CWE-352 (Cross-Site Request Forgery) in the context of unauthorized resource loading. Organizations and users should immediately update to the patched versions of WhatsApp for Android and WhatsApp Business to mitigate this risk, as the vulnerability could be exploited in the wild without user interaction, making it particularly concerning for enterprise security environments where such applications are widely deployed. The patch implemented by WhatsApp addressed the URL validation logic to properly sanitize input parameters before initiating any external resource loading operations, thereby preventing automatic execution of attacker-controlled URLs.