CVE-2025-30401 Overview
A spoofing vulnerability has been identified in WhatsApp for Windows that exploits a mismatch between MIME type display and file extension handling. The application displays attachments based on their MIME type but determines the file opening handler using the attachment's filename extension. This discrepancy allows attackers to craft malicious attachments that appear benign but execute arbitrary code when manually opened by the recipient within WhatsApp.
Critical Impact
Attackers can trick users into executing malicious code by sending specially crafted attachments that disguise executable files as harmless content types like images or documents.
Affected Products
- WhatsApp for Windows versions prior to 2.2450.6
- WhatsApp Desktop application on Windows platforms
Discovery Timeline
- April 5, 2025 - CVE-2025-30401 published to NVD
- April 9, 2025 - Last updated in NVD database
Technical Details for CVE-2025-30401
Vulnerability Analysis
This vulnerability represents a spoofing issue caused by inconsistent file type handling within WhatsApp for Windows. The application utilizes two different mechanisms for processing attachments: the MIME type determines how the attachment is displayed to the user, while the filename extension dictates which application handles the file when opened. An attacker can exploit this inconsistency by crafting an attachment with a benign MIME type (such as image/jpeg) but a dangerous file extension (such as .exe or .bat).
When a recipient views the attachment in the WhatsApp interface, it appears to be a safe file type based on the MIME type presentation. However, when the user manually opens the attachment within WhatsApp, the operating system's file association mechanism takes over, selecting the handler based on the filename extension rather than the MIME type. This results in the execution of potentially malicious code instead of simply viewing the expected content.
Root Cause
The root cause stems from a fundamental design flaw where WhatsApp for Windows fails to properly validate and correlate MIME types with their corresponding filename extensions. The application trusts the MIME type for display purposes but defers to the operating system's extension-based file handler selection when opening files. This trust boundary mismatch creates an exploitable condition where the visual representation of a file does not match its actual behavior upon execution.
Attack Vector
The attack requires network access and involves sending a maliciously crafted attachment through WhatsApp messaging. The attacker must create a file with a manipulated MIME type header that differs from its actual file extension. When the target receives the message, they see what appears to be an innocuous file (like an image). Upon manually opening the attachment within WhatsApp, the Windows operating system processes the file based on its extension, potentially launching an executable or script instead of an image viewer.
The attack requires user interaction, as the recipient must manually choose to open the attachment. Social engineering tactics may be employed to entice the victim to open the malicious file.
Detection Methods for CVE-2025-30401
Indicators of Compromise
- Received WhatsApp attachments where the displayed file type does not match the actual file extension
- Unexpected process executions immediately following the opening of WhatsApp attachments
- Suspicious executable files or scripts appearing in WhatsApp download directories
- Unusual outbound network connections originating from processes spawned after opening WhatsApp attachments
Detection Strategies
- Monitor WhatsApp attachment directories for files with mismatched MIME types and extensions
- Implement endpoint detection rules that alert on executable launches from WhatsApp-associated folders
- Deploy file integrity monitoring on WhatsApp download locations to detect suspicious file creations
- Utilize behavioral analysis to identify unusual child processes spawned from WhatsApp Desktop
Monitoring Recommendations
- Enable enhanced logging for file system operations within WhatsApp data directories
- Configure SIEM rules to correlate WhatsApp attachment downloads with subsequent process executions
- Monitor for registry modifications or persistence mechanisms following WhatsApp attachment interactions
- Review network traffic patterns for anomalous connections initiated after opening attachments
How to Mitigate CVE-2025-30401
Immediate Actions Required
- Update WhatsApp for Windows to version 2.2450.6 or later immediately
- Educate users about the risks of opening attachments from unknown or untrusted sources
- Implement application control policies to restrict executable launches from WhatsApp directories
- Consider temporarily disabling automatic attachment downloads until the update is applied
Patch Information
WhatsApp has addressed this vulnerability in version 2.2450.6 for Windows. Organizations and users should update to this version or later to remediate the spoofing issue. The fix ensures proper correlation between MIME type display and file extension handling, preventing the mismatch exploitation. For detailed information, refer to the Facebook Security Advisory and the WhatsApp Security Advisory.
Workarounds
- Avoid opening attachments directly within WhatsApp; instead, scan all files with antivirus software before opening
- Configure Windows to display file extensions for all files to help identify mismatches
- Use application whitelisting to prevent unauthorized executables from running
- Implement network-level filtering to scan WhatsApp attachments for malicious content before delivery
# Windows configuration to always show file extensions
# Run in PowerShell with Administrator privileges
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" -Name "HideFileExt" -Value 0
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
