CVE-2025-30401 in WhatsApp Desktop
Summary
by MITRE • 04/05/2025
A spoofing issue in WhatsApp for Windows prior to version 2.2450.6 displayed attachments according to their MIME type but selected the file opening handler based on the attachment’s filename extension. A maliciously crafted mismatch could have caused the recipient to inadvertently execute arbitrary code rather than view the attachment when manually opening the attachment inside WhatsApp.
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Analysis
by VulDB Data Team • 04/05/2025
This vulnerability in WhatsApp for Windows represents a critical file handling inconsistency that exploits the difference between MIME type and filename extension validation mechanisms. The flaw exists in the application's attachment processing logic where the user interface displays files based on their actual MIME type while the underlying file execution handler relies on the filename extension. This discrepancy creates a potential attack vector where a malicious actor could craft an attachment with a misleading filename extension that does not match its actual MIME type. The vulnerability is particularly concerning because it leverages user trust and the expected behavior of file handling applications. When users manually open attachments within WhatsApp, the application's file handler would execute the file based on its extension rather than its actual content type, potentially leading to unintended code execution. This issue demonstrates a classic security anti-pattern where different validation layers operate on different criteria, creating a gap that attackers can exploit.
The technical implementation of this vulnerability stems from WhatsApp's failure to maintain consistent file type validation across its processing pipeline. When a file is received, the application parses the MIME type for display purposes but does not enforce the same validation for execution decisions. This creates a scenario where a file with a .pdf extension could actually contain executable code, or conversely, a file with a .exe extension might be a legitimate image. The flaw aligns with CWE-150, which addresses the improper handling of inconsistent input validation, and reflects a breakdown in the principle of least privilege where the application should not execute files based on potentially misleading metadata. From an operational perspective, this vulnerability represents a significant risk because it requires no special privileges or complex attack vectors, relying instead on social engineering to convince users to manually open attachments. The attack surface is broad since WhatsApp processes numerous attachment types including documents, images, audio, and video files, each of which could be crafted to exploit this inconsistency.
The impact of this vulnerability extends beyond simple code execution to encompass potential privilege escalation and system compromise scenarios. When a maliciously crafted file executes based on its filename extension rather than its actual content, it could potentially trigger the execution of malware, trojans, or other harmful code. This risk is exacerbated by the fact that users often trust applications like WhatsApp to handle files safely, especially when the interface displays a familiar file type such as a PDF or image. The vulnerability also aligns with ATT&CK technique T1059 which covers execution through command and scripting interpreters, as the malicious file execution could occur through PowerShell, batch files, or other system interpreters. Additionally, this flaw could enable more sophisticated attacks such as phishing campaigns where the malicious attachment appears legitimate due to proper MIME type display but executes harmful code upon user interaction. Organizations and individuals using WhatsApp for Windows should consider this vulnerability as a potential entry point for more comprehensive attacks, particularly in environments where file execution policies are not strictly enforced.
The recommended mitigations for this vulnerability focus on both immediate remediation and long-term architectural improvements. The most direct solution involves updating WhatsApp to version 2.2450.6 or later where the inconsistency between MIME type display and filename extension handling has been resolved. This update ensures that file execution decisions are consistently based on the actual file content rather than potentially misleading extensions. Organizations should also implement additional security controls such as email filtering rules that block suspicious file types, network-based file inspection systems, and user education programs about the risks of manually opening attachments from unknown sources. From a defensive perspective, implementing application whitelisting policies and restricting file execution based on content type rather than extension can provide additional protection layers. Security teams should monitor for indicators of compromise related to this vulnerability, including unusual file execution patterns or attempts to access system resources through WhatsApp processes. The vulnerability also highlights the importance of consistent validation across all application layers and the need for security testing that specifically addresses scenarios where different validation criteria might conflict, ensuring that future applications maintain integrity across all processing stages.