CVE-2020-1891 in WhatsApp
Summary
by MITRE
A user controlled parameter used in video call in WhatsApp for Android prior to v2.20.17, WhatsApp Business for Android prior to v2.20.7, WhatsApp for iPhone prior to v2.20.20, and WhatsApp Business for iPhone prior to v2.20.20 could have allowed an out-of-bounds write on 32-bit devices.
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Analysis
by VulDB Data Team • 11/12/2020
This vulnerability affects the video call functionality in WhatsApp applications across both android and ios platforms, specifically targeting devices running 32-bit architectures. The issue stems from improper input validation within the video call parameter handling mechanism, where user-controlled data is processed without adequate bounds checking. The flaw allows an attacker to manipulate video call parameters in a manner that could lead to memory corruption through out-of-bounds write operations. This type of vulnerability represents a critical security weakness that can potentially be exploited to execute arbitrary code or cause application crashes. The vulnerability specifically impacts devices with 32-bit processors due to the memory addressing limitations and data handling characteristics inherent to these architectures.
The technical implementation of this vulnerability involves the manipulation of video call parameters that are passed through the application's communication stack. When processing user-controlled input for video call initiation or configuration, the application fails to properly validate the size or bounds of the data being processed. This allows an attacker to craft malicious parameters that exceed the allocated memory boundaries, resulting in an out-of-bounds write condition. The vulnerability is particularly concerning because it affects multiple platforms and application variants, indicating a systemic issue in the codebase rather than a isolated incident. The 32-bit architecture limitation means that memory addressing constraints make such buffer overflows more likely to result in exploitable conditions.
The operational impact of this vulnerability extends beyond simple application instability to potentially enable remote code execution on affected devices. An attacker could leverage this vulnerability to gain unauthorized access to the device, potentially leading to data theft, surveillance capabilities, or further exploitation within the device's ecosystem. The widespread adoption of WhatsApp across global populations makes this vulnerability particularly dangerous as it could affect millions of users simultaneously. The vulnerability's presence in both regular WhatsApp and WhatsApp Business applications indicates that the security flaw exists in core functionality rather than in specialized features, increasing the attack surface significantly.
Mitigation strategies for this vulnerability should focus on immediate patch deployment across all affected platforms and versions, with particular attention to the 32-bit device population that remains vulnerable. Organizations should implement network monitoring to detect potential exploitation attempts and ensure that all endpoints are updated to the latest secure versions. The fix typically involves implementing proper bounds checking and input validation mechanisms within the video call parameter processing code. Security teams should also consider implementing additional network security controls such as deep packet inspection to identify and block suspicious parameter sequences. This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a clear example of how mobile application security flaws can be exploited for remote code execution. The ATT&CK framework would categorize this as a privilege escalation technique through application exploitation, potentially leading to persistent access within the target device.