Tag Archives: Website Backdoor

P.A.S. Fork v. 1.0 — A Web Shell Revival

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, if these popular (and readily available) PHP web shells do the job, there’s no need […]

Backdoor Shell Dropper Deploys CMS-Specific Malware

A large majority of the malware we find on compromised websites are backdoors that allow an attacker to maintain unauthorized access to the site and execute whatever commands they want. Another common scenario includes malware which is directly injected into a website’s files and used to redirect traffic, steal credit cards and other sensitive information, […]

Backdoor Obfuscation: tempnam & URL Encoding

In an attempt to avoid detection, attackers and malware authors are always experimenting with different methods to obfuscate their malicious code. During a recent investigation, we came across an interesting backdoor that was leveraging encoding along with common PHP functions to conceal its operations from any active security systems on the host. This PHP web […]

The Hidden PHP Malware that Reinfects Cleaned Files

Website reinfections are a serious problem for website owners, and it can often be difficult to determine the cause behind the reinfection — especially if you lack access to necessary logs, which is usually the case for shared hosting services. Some of the more common causes of reinfections are issues like cross- site contamination or […]

Using assert() to Execute Malware in PHP 7 Environments

Initially released December 2015, PHP 7 introduced a multitude of performance and security improvements. Approximately 43.7% of websites across the web currently use PHP 7.x, making it an incredibly popular scripting language — which is likely why attackers are creating malware to target environments which leverage it. During a recent investigation, our team stumbled across […]

Smoker Backdoor: Evasion Techniques in Webshell Backdoors

“Smoker Backdoor” is a PHP webshell backdoor that uses hexadecimal and decimal obfuscation in conjunction with the PHP function goto to evade detection from malware scanners. The hexadecimal/decimal obfuscation is clear to see when viewing the file’s PHP code. For instance, this section of the PHP code is obfuscated using this method: if ($_GET[“x72145156x61155x65”] == […]

PHP Backdoor Obfuscated One Liner

In the past, I have explained how small one line PHP backdoors use obfuscation and strings of code in HTTP requests to pass attacker’s commands to backdoors. Today, I’ll highlight another similar injection example and describe some of the malicious behavior we’ve seen recently on compromised websites. Obfuscated PHP Backdoor Discovered by our Remediation team, […]

Vulnerabilities Digest: July 2020

Relevant Plugins and Vulnerabilities: Plugin Vulnerability Patched Version Installs Asset CleanUp: Page Speed Authenticated XSS 1.4.6.7 80000 Quiz And Survey Master Authenticated Stored XSS 7.0.0 30000 Comments – wpDiscuz 7.0.0 – Arbitrary File Upload 7.0.5 70000 Real Estate 7 Reflected XSS 3.0.4 8000 CarePlus Reflected XSS — 5000 WooCommerce Subscriptions Unauthenticated Stored XSS 2.6.3 10000 […]

Malicious Magento User Creator

We recently found a simple malicious script leveraging Magento’s internal functions to create a new admin user with the admin role “Inchoo” ⁠— probably referring to a Croatian Magento consulting company. The script is simple but very effective and can easily be overlooked as another Magento file without closer inspection. It’s based on a sample […]