Last month, we came across an ongoing JavaScript-based malware campaign affecting compromised websites. The malware injects a fullscreen iframe that silently loads content from a suspicious external domain. This type of malicious script aims to force users to view unsolicited content, often for ad fraud, traffic generation, or…
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WordPress Vulnerability & Patch Roundup — July 2025
Vulnerability reports and responsible disclosures are essential for website security awareness and education. Automated attacks targeting known software vulnerabilities are one of the leading causes of website compromises. To help educate website owners about potential threats to their environments, we’ve compiled a list of important security updates and…
Why Your Website Might Be Throwing a 421 SNI Error (And What to Do About It)
So, your support team is suddenly flooded with tickets about “421 Misdirected Request” errors, and you’ re wondering if the internet is just having a bad day. Spoiler: it’s not. But Apache might be. Let’s break down what’s going on, why it’s happening now, and how to fix it—whether…
Unauthorized Admin User Created via Disguised WordPress Plugin
Recently at Sucuri, we investigated a malware case reported by one of our clients. Their WordPress site was compromised, and the attacker had installed a fake plugin. Upon analysis revealed that it was a sophisticated backdoor plugin designed to create a persistent and hidden administrator account. What Did…
Uncovering a Stealthy WordPress Backdoor in mu-plugins
Recently, our team uncovered a particularly sneaky piece of malware tucked away in a place many WordPress users don’ t even know exists: the mu-plugins folder. In fact, back in March, we saw a similar trend with hidden malware in this very directory, as detailed in our post Hidden…
Product Update – New Backups Platform
Sucuri is pleased to announce the completion of a product upgrade with our new Backups platform. For those already subscribed to our Backups platform, you will begin to see (over the next week or so), a new destination for where to access your new Backups. For those who…
WordPress Redirect Malware Hidden in Google Tag Manager Code
Last month, a customer contacted us after noticing their WordPress website was unexpectedly redirecting to a spam domain. The redirection occurred approximately 4-5 seconds after a user landed on the site. Upon closer inspection of the site’s source code we found a suspicious Google Tag Manager loading. This…
Stealthy PHP Malware Uses ZIP Archive to Redirect WordPress Visitors
Last month, a customer contacted us, concerned about persistent and inexplicable redirects on their WordPress website. Our investigation quickly unearthed a sophisticated piece of malware deeply embedded within their site’ s core files. This wasn’ t just a simple redirect; it was a complex operation designed for search engine poisoning…
Attackers Inject Code into WordPress Theme to Redirect Visitors
In a recent article we discussed some of the reasons sites are frequently attacked. That article covered browser redirects, and we’ll explore an example of such a case here. Website themes are a common attack vector for many reasons. The theme is guaranteed to load on every page, …
Fake Spam Plugin Uses Victim’s Domain Name to Evade Detection
During our investigation of an SEO spam infection (spam content designed to manipulate search engine results), we discovered a nicely crafted plugin that named itself after the infected domain, helping it evade detection. While this tactic was simple, it easily blended in with other legitimate plugins, making it…
Vulnerability & Patch Roundup — June 2025
Vulnerability reports and responsible disclosures are essential for website security awareness and education. Automated attacks targeting known software vulnerabilities are one of the leading causes of website compromises. To help educate website owners about potential threats to their environments, we’ve compiled a list of important security updates and…
Stealthy WordPress Malware Drops Windows Trojan via PHP Backdoor
Last month, we encountered a particularly interesting and complex malware case that stood out from the usual infections we see in compromised WordPress websites. At first glance, the site looked clean, no visible signs of defacement, no malicious redirects, and nothing suspicious in the plugin list. But beneath…
The Case of Hidden Spam Pages
Spammy posts and pages being placed on WordPress websites is one of the most common infections that we come across. The reason being is that the attack is very low-level in terms of sophistication: All that is required of the attacker is to brute force their way into…
Malicious WordPress Plugin Creates Hidden Admin User Backdoor
I recently wrote about a case where a malicious plugin was used to steal admin credentials. Here we will examine yet another malicious plugin that creates a malicious admin user right in the website. Examining the malware While examining the site, we noticed a plugin located at wp-content/plugins…
Analysis of a Malicious WordPress Plugin: The Covert Redirector
A few weeks ago, we received a support request from a website owner who was experiencing unexpected redirects. Visitors landed on the website normally, but after about 4–5 seconds, the site redirected them to unrelated and suspicious websites. During the investigation, we discovered a malicious plugin that was…
Understanding SSRF: Abusing Server Trust from the Inside Out
In our daily interactions online, trust is a fundamental currency. We trust servers to handle our data, process our requests, and reliably deliver content. But what happens when that trust is abused and turned against the server itself? What if an attacker could trick your server into becoming…
Fake WordPress Caching Plugin Used to Steal Admin Credentials
A common trend we see is that bad actors will upload malicious plugins to WordPress sites. These plugins serve a wide variety of functions from injecting spam to redirecting sites to other malicious content. In this article we will examine a more dangerous method where plugins can be…
Vulnerability & Patch Roundup — May 2025
Vulnerability reports and responsible disclosures are essential for website security awareness and education. Automated attacks targeting known software vulnerabilities are one of the leading causes of website compromises. To help educate website owners about potential threats to their environments, we’ve compiled a list of important security updates and…
What Motivates Website Malware Attacks?
The depiction in the media of hackers tends to be that of balaclava-wearing villains who type furiously in a dark basement, motivated by nothing but evil intentions. However, while this may be true in some instances, by and large the determining factors that result in malware attacks are…
Fake Java Update Popup Found in Malicious WordPress Plugin
We recently assisted a customer who reported a persistent and concerning “ Java Update” pop-up appearing on their WordPress website. This type of deceptive notification is a common tactic used by attackers to compromise website visitors. Our investigation revealed a malicious plugin operating stealthily within their WordPress environment. What…
