WhatsApp Vulnerability Allows Python, PHP Script Execution

A security flaw in WhatsApp for Windows allows Python and PHP scripts to execute without warning when opened by recipients. This vulnerability, affecting users with Python installed on their systems, could pose a risk to software developers, researchers, and power users.

The flaw enables the execution of Python and PHP scripts from directly within the WhatsApp client, bypassing any security prompts. Users who click "Open" on these file types will inadvertently execute the scripts, potentially exposing their systems to malicious code. The issue was discovered by IT security expert Saumyajeet Das, who found that these file types are not blocked by WhatsApp's current security measures.

This vulnerability is reminiscent of a similar issue that affected Telegram for Windows in April this year, where attackers could bypass security warnings and execute remote code by sending Python scripts. Telegram addressed the issue after it was reported, but WhatsApp has not taken similar action.

WhatsApp for Windows does block several high-risk file types, such as:

• .exe
• .com
• .scr
• .bat
• .dll
• .hta
• VBS

Python and PHP scripts are not included in this blocklist, allowing them to be executed directly from the application.

Meta, the parent company of WhatsApp, was informed of the vulnerability on June 3. Despite acknowledging the issue on July 15, Meta has not implemented a fix. In a statement to BleepingComputer, Meta indicated that they consider it the users' responsibility to avoid opening unknown files.

"We've read what the researcher has proposed and appreciate their submission. Malware can take many different forms, including through downloadable files meant to trick a user," said a Meta spokesperson. "It's why we warn users to never click on or open a file from somebody they don't know, regardless of how they received it — whether over WhatsApp or any other app."

The vulnerability's impact could be substantial, particularly if malicious attachments are posted in public or private WhatsApp chat groups, potentially affecting multiple recipients. Das expressed concern about the risk of malicious code transfer in such scenarios and suggested that Meta could mitigate the issue by adding Python scripts to their blocklist.

As of the latest reports, the vulnerability remains unaddressed in the current version of WhatsApp for Windows. Users are advised to exercise caution and avoid opening files from unknown sources to protect their systems from potential threats.