Understanding and Resolving False Malware Alerts in Post SMTP Plugin

If your security software or web host has recently flagged the Post SMTP plugin for a potential malware or virus threat, you're not alone. This is a common and often frustrating occurrence for many users. This article explains why these false positives happen and what you can do to verify your site's safety.

Why Is This Happening?

Security scanners work by detecting patterns in code that are known to be used by malicious software. The Post SMTP plugin, particularly in its notification and third-party SDK code, uses certain PHP functions and encoding techniques that can sometimes match these patterns, leading to a false positive alert.

Based on common user reports, files that are frequently flagged include:

• wp-content/plugins/post-smtp/Postman/Extensions/Core/Notifications/PostmanPushoverNotify.php
• Files within the /freemius/ directory, such as FreemiusBase.php and class-freemius.php

The code in these files is legitimate. For example, the PostmanPushoverNotify.php file handles secure communication with the Pushover notification service, while the Freemius files are part of a commercial SDK used for licensing and update functionality by many reputable WordPress plugins.

How to Verify It's a False Positive

Before taking any action, it's important to confirm the alert is incorrect. Here are the recommended steps:

1. Check the Plugin Source: The Post SMTP plugin is open-source. Its code is publicly available for review on platforms like WordPress.org. Many developers and security experts scrutinize this code, making a widespread, undetected malware issue highly unlikely.
2. Cross-Reference with VirusTotal: Upload the flagged file(s) to VirusTotal.com. This service checks files against dozens of antivirus engines. If only one or two scanners flag it while others report it as clean, it is almost certainly a false positive.
3. Confirm You Are Updated: Always ensure you are running the latest version of the Post SMTP plugin. The development team routinely addresses issues and, in some cases, may adjust code to prevent these false flags in new releases. The sample threads indicate that version 3.1.1 was a relevant update in this context.

What to Do Next

If you've confirmed it is a false positive, you have a few options:

• Whitelist the Files: Most security plugins and hosting control panels allow you to whitelist specific files or directories from scans. You can add the paths to the flagged Post SMTP files to this whitelist.
• Report the False Positive: Help improve the security software for everyone by reporting the false positive to the vendor of your antivirus or malware scanner. They can update their definitions to avoid flagging this legitimate code in the future.
• Re-install the Plugin: For absolute peace of mind, you can delete the plugin and install a fresh copy directly from the WordPress Plugin Repository. This guarantees you have the authentic, unmodified code.

While alarming, these security warnings are typically a sign of an overly cautious scanner rather than a compromised website. By following these steps, you can confidently verify the integrity of your Post SMTP plugin and resolve any erroneous alerts.