We sometimes find malware code injections that contain strange code comments, which are normally used by programmers to annotate a section of code — for example, a short description of a feature or functionality for other developers to reference. Oftentimes,…
We’ve seen a wider variety of PHP web shells being used by attackers this year — including a number of shells that have been significantly updated in an attempt to “improve” them. Depending on the scope of changes and feature…
During malware analysis, we regularly find variations of this injected script on various compromised websites: . The variable “_0x446d” assigns hex encoded strings in different positions in the array. If we get the ASCII representation of the variable, we’ll end…
This summer, MalwareBytes researcher Jérôme Segura wrote an article about how criminals use image files (.ico) to hide JavaScript credit card stealers on compromised e-commerce sites. In a tweet, Affable Kraut also reported another similar obfuscation technique using .ico files…
WordPress released version 5.5.2 yesterday, which fixed a reflected XSS vulnerability we reported earlier this year. The root cause of this issue is a bug in the way WordPress determines a user’s current page, and which may cause a few…
A PHP shell containing multiple functions can easily consist of thousands of lines of code, so it’s no surprise that attackers often reuse the code from some of the most popular PHP web shells, like WSO or b374k. After all,…
We often see hackers reusing the same malware, with only a few new adjustments to obfuscate the code so that it is more difficult for scanning tools to detect. However, sometimes entirely new attack tools are created and deployed by…
During a recent investigation, we found an infected website was redirecting to YouTube after its main index.php file had been modified to include the following line of HTML: <meta http-equiv=’refresh’ content=’2;url=https://youtu.be/fsqzjDAO2Ug’> This technique works because it’s possible to use HTML…