Error 403 – Forbidden can be a frustrating interruption to anyone’s day. This common error can lead to exasperated website visitors, even resulting to lost traffic and website revenue depending on which page of your site is affected. When you (or your site visitors) encounter an unexpected error 403 message, it’s important to assess the issue promptly just in case it’s a symptom of a more serious issue on your site.
You might run into a 403 forbidden error when visiting a website directory or page with restricted permissions, as most websites are set up to disallow directory browsing to protect sensitive files. But in some cases, 403’s can be an indicator of compromise — stemming from by or faulty malware, or a damaged .htaccess file on your website.
In this article, we will dive into the different types of HTTP 403 errors, their possible causes, and provide step-by-step instructions on how to troubleshoot and resolve these errors to get your website back online.
Contents:
- What is error 403?
- How are 403 errors different from other 4xx errors?
- What causes a 403 error?
- How do I fix a 403 error on my site?
What is error 403?
The HTTP Error 403 response status code is a client-side error that signifies the server has received and understood the request but is unable to authorize it.
A 403 Forbidden: you don’t have permission to access this resource error typically occurs when a user does not have the necessary permission to access a specific web page or resource on a web server. This error is usually an issue with the website itself — rather than a problem on the user’s side.
400 error messages can come in all sorts of flavors, but they all mean the same thing. Here are a few variations of 400 errors you might encounter in your browser:
- 403 Forbidden
- Error 403
- HTTP 403
- Error 403 – Forbidden
- HTTP Error 403 – Forbidden
- Forbidden: You don’t have permission to access [directory] on this server
- Forbidden
These are only a handful of the possible messages you might find when encountering a 403 error. In fact, some websites even have their own custom 403’s.
How are 403 errors different from other 4xx errors?
To help you understand the difference between generic 400 errors and other types of client-side errors, we’ve outlined some of the common types of 4xx responses you might encounter on your site.
| Client Error | Description |
| 400: Bad Request | This indicates that the server was unable to process the request due to malformed syntax or invalid data provided by the client. |
| 401: Unauthorized | This means the request requires authentication, and the client has not provided valid credentials or has insufficient access rights. |
| 402: Payment Required | Although not widely used, this error code indicates that the requested resource requires payment before it can be accessed. |
| 403: Forbidden | The client does not have the necessary permissions to access the requested resource, even if they are authenticated. |
| 404: Not found | The requested resource is not found on the server, usually because the URL is incorrect or the resource has been removed. |
| 405: Method Not Allowed | The HTTP method used in the request is not supported for the specified resource. |
| 406: Not Acceptable | The server cannot produce a response that matches the criteria specified by the client in the request headers. |
| 407: Proxy Authentication Required | This is similar to a 401 error, but it indicates that the client must authenticate itself with the proxy server before accessing. |
| 408: Request Timeout | The server did not receive a complete request from the client within the allotted time frame. |
| 409: Conflict | The requested operation could not be completed due to a conflict with the current state of the resource. |
| 410: Gone | The requested resource is no longer available on the server and has been permanently removed. |
| 411: Length Required | The server requires a valid Content-Length header in the request for the specified resource. |
| 412: Precondition Failed | One or more preconditions specified by the client in the request headers have not been met by the server. |
With the exception of a 400 error, the majority of client-side errors provide clear reasons for the status response that can help you pinpoint the issue and resolve it.
What causes error 403?
Error 403 – Forbidden messages can occur for a myriad of reasons, including misconfigured website or server files, incorrect file permissions, or issues with recently installed plugins or third-party software. In rarer cases, 403 errors can also be an indicator of compromise, as some malware infections are notorious for infecting the .htaccess file, resulting in errors and unexpected website behavior.
The most common causes of a 403 error include:
- Restricted directories or pages. Most websites are set up to disallow directory browsing to protect sensitive files or prevent access to restricted areas.
- Incorrect file or folder permissions. If permissions have been incorrectly set or altered to restrict access to resources, visitors may not be able to read the contents of the web page.
- Corrupt .htaccess file. Corrupted or incorrect settings in the .htaccess file can lead to 403 errors, which may occur after making changes to the file or after .
- WordPress plugin issues. A WordPress plugin that is improperly configured, incompatible with another plugin, or affected by a malware infection can trigger 403 errors.
- Missing index page. Your site’s homepage is not one of the web server’s default index files: index.html, index.php, default.asp, index.htm, index.shtml, etc..
- Incorrect IP address. Domain name points to an incorrect IP address.
- Malware infection. Some malware infections are renowned for causing 403 errors on compromised websites.
When encountering a 403 error, users are denied access to particular areas of a website, which might happen when landing on a webpage with a permission error or an empty website directory. You’ll want to address these errors as soon as possible to ensure a smooth user experience.
How do I fix error 403 on my site?
Sometimes, the simplest solutions can solve the most complex problems – especially when it comes to 403’s on your site. Let’s start with the basics and explore each step in detail.
Continue in chronological order until the issue is resolved:
1. Verify the address and refresh the page
The first thing you should do when encountering a 403 error is double-check the URL you’re trying to access. A common cause of 403 errors is an incorrect URL or a mistyped address. Ensure that the address is spelled correctly and points to the correct resource.
If the address is a directory and not a specific web page, you may encounter a 403 error, as some web servers might restrict direct access to directories. If that doesn’t work, try reloading the page (F5/Ctrl + F5).
Reloading is a simple action, but it can often resolve temporary issues. There’s a possibility that your request was processed during a momentary server hiccup, and refreshing the page might be all it takes to resolve the error.
2. Clear your browser cache
Your browser cache helps speed up the loading time of websites by storing static resources like images, scripts, and stylesheets. However, sometimes discrepancies can occur between the actual version of a page and its cached version, leading to errors such as the 403 Forbidden error.
To resolve this issue, clear your browser’s cache. This action will force your browser to fetch the most recent version of the web page directly from the server.
After clearing your cache, revisit the page to see if the error has been resolved. You can ensure that you are not seeing a cached page on the website by loading the URL with an appended variable like this: example.com?nocache
3. Modify your file and directory permissions
Each file and folder on your website’s server has unique file permissions that control read, write, and execute access. These permissions are represented by a three-digit number, with each digit indicating the level of permission for the owner, group, and others respectively.
Occasionally, file permissions can be accidentally altered or incorrectly set, leading to a 403 Forbidden error. To resolve this issue, you’ll need to connect to your server via FTP/SFTP and review your site’s file permissions.
The ideal file permissions for a WordPress site are:
- Files: 644 or 640
- Directories: 755 or 750
- wp-config.php: 440 or 400
To modify file permissions for your WordPress site:
- Connect to your server using an SFTP client.
- Navigate to your site’s root folder (often called public_html or www).
- Locate the files and folders that need their permissions adjusted, right-click on them, and select File Permissions or Properties.
- Update the permissions as necessary, and be sure to apply these changes recursively if adjusting folder permissions.
4. Check for recently installed or updated software
Investigate to see if any recently installed or upgraded software on your website failed to install or upgrade. To refresh your software, check the vendor’s website for specific instructions.
You’ll also want to audit your website for any new and unfamiliar plugins or themes. If you find anything unusual, this may be an indicator of compromise.
Investigate further to pinpoint:
- What the unfamiliar software or component is
- How long it’s been installed on your site
- Whether or not it’s legitimate
If you encounter anything that looks suspicious, remove the component and scan your website for malware.
Important note: Attackers regularly scan outdated and poorly maintained plugins, themes, and components for known vulnerabilities. Always keep your software patched with the latest security updates to mitigate risk and protect against automated attacks.
5. Check your .htaccess file
The .htaccess file is a configuration file used by the Apache web server to control various aspects of your website, such as redirects, access restrictions, and performance optimizations. Errors in the .htaccess file, like incorrect syntax or conflicting rules, can result in a 403 Forbidden error. The most common source of such errors are incorrectly configured allow/deny rules. Unwanted deny rules are also known to be added to random subdirectories by some types of malware.
Since .htaccess files can be placed in any directory and their directives affect all subdirectories, you should start from the level where you get the 403 error and check for .htaccess files in every directory up to the root.
If you’re a cPanel user, you can follow these steps to troubleshoot the issue:
- Navigate to your cPanel File Manager.
- Go to the public_html directory and locate your .htaccess file. If you only have this error for a specific directory, check if this directory has its own .htaccess file.
- Right click on the file in your cPanel file manager and Download a copy to back it up.
- Once you’ve verified that you now have a backup copy of your .htaccess file, you can right click the file again and select Delete.
- Check your website to see if the 403 error is resolved. If your site now works as expected, your .htaccess file was corrupted and you’ll need to make a new one.
- Log in to your WordPress dashboard and navigate to Settings > Permalinks, then click on Save Changes at the bottom of the page to generate a new .htaccess file for your website.
6. Deactivate your plugins
Faulty or incompatible plugins can cause 403 Forbidden errors on your website. To identify the problematic plugin, you will need to deactivate your plugins and then reactivate them one by one, checking your site after each activation to see if the error reappears.
If you’re unable to access your WordPress dashboard to deactivate your plugins, you can follow these steps to troubleshoot your components:
- Make a backup of your website.
- Connect to your server via SFTP.
- Navigate to the wp-content folder.
- Rename the plugins folder to something like plugins-disabled to simultaneously disable all of your plugins on your site.
- Check your website for issues. If the error is gone, it’s likely that a plugin was causing the issue.
- Rename the folder back to plugins and reactivate your plugins one by one, checking your site after each activation to pinpoint the problematic component.
- Once the culprit is identified, update or delete the plugin as needed.
7. Temporarily deactivate your CDN
If you’re getting 403 errors on your assets (images, JavaScript, CSS), it could be an issue with your content delivery network (CDN). CDNs can sometimes block access to certain resources due to misconfigurations or security policies.
To check if the CDN is causing the error, temporarily disable it and visit your site again. Once the issue is resolved, you can re-enable your CDN to continue benefiting from its performance optimizations.
Troubleshooting 403’s with the Sucuri WAF
If you’re a Sucuri WAF user and you’ve implemented Firewall Bypass Prevention for your Firewall, then you will need to add your own IP address (which can be found here) to the FileMatch directive in your .htaccess file to resolve 403 issues:
# BEGIN Sucuri Firewall Bypass Prevention <FilesMatch ".*"> Order deny,allow Deny from all Allow from 192.88.134.0/23 Allow from 185.93.228.0/22 Allow from 66.248.200.0/22 Allow from 208.109.0.0/22 Allow from 2a02:fe80::/29 Allow from INSERT YOUR IP HERE </FilesMatch> # END Sucuri Firewall Bypass Prevention
8. Check for hotlink protection configuration issues
Hotlink protection prevents other websites from using your server’s bandwidth by directly linking to your files. When hotlink protection is enabled, it typically returns a 403 forbidden error to unauthorized requests. However, misconfigured hotlink protection can also block legitimate requests and cause 403 errors.
To resolve this issue, review your hotlink protection settings either in your hosting control panel or CDN settings. Ensure that the protection is correctly configured to block unauthorized requests only. If necessary, update the settings and test your site again to see if the error has been resolved.
9. Disconnect from your VPN
Some websites block access to users connected through a VPN to prevent potential abuse or circumvention of geo-restrictions.
For those using a VPN, try disconnecting from it and accessing the site directly or through another server provided by your VPN service. If the error disappears, the 403 Forbidden error was likely due to your VPN connection.
10. Scan your website for security issues and malware
In some cases, infected components or .htaccess malware can result in 403 errors on your website. You’ll want to perform an extensive scan of your website’s files and server to rule out a compromise or infection causing the error.
11. Reach out to your hosting provider
If none of the above solutions worked for you, it’s time to contact your hosting provider for assistance. They can help you pinpoint the issue, provide guidance on resolving it, and even fix it on your behalf if the problem lies within the server configuration or hosting infrastructure.
Protecting your website against 403’s
Encountering a 403 error on your website can be a frustrating experience, but it’s essential to address the issue promptly to avoid losing valuable traffic and harming your site’s reputation.
By getting a grip on the various forms of 403 errors and following the comprehensive troubleshooting steps laid out in this post, you’ll be well-equipped to squash these errors and bring your site back on track. Furthermore, always make sure your site is up-to-date and hardened against potential threats.
If you’ve followed these troubleshooting steps and suspect that website malware is the culprit, you can refer to our guide on how to clean up a hacked website or reach out to us for support – our experienced security analysts are available 24/7 to help clean up malware on a website.
Fernando Barbosa
Krasimir Konov
Nathan Chaddock
Eli Trevino![Malware comes in many different varieties. Analyst Krasimir Konov is on this month’s Sucuri Sit-Down to help keep them all straight. From malicious iframes to SEO spam, join host Justin Channell as he racks Krasimir’s brain on all the different types of malware. Also, Krasimir discusses his recent blog post about a malicious cURL downloader, and Justin breaks down the latest website security news, including patched plugins you should update. Podcast Transcript Justin Channell: Hello, and welcome to the Sucuri Sit Down. I'm your host, Justin Channell, and this is a monthly podcast about website security, where we get in-depth with the malware removal experts here at Sucuri. Later in the show, I'll have our analyst Krasimir Konov to chat about some different types of malware, but first, let's take a look at other topics we've published on our blog and Sucuri labs notes this month. First up, we have some new information about credit card skimming with hackers using a hybrid method to steal payment information from eCommerce websites. Our analyst Dennis Sinegubko wrote about this for the Sucuri blog back at the beginning of June. Now, most credit card stealing malware is a client side JavaScript that grabs data and sends it to a third party server. But, that approach has a drawback for bad actors because it's still possible to track the requests and catch them as being suspicious. Now, to get around that, bad actors have started harvesting information server side by modifying core PHP files. In this case, the infection would be undetectable from the outside, but it's still going to be pretty easy to find because you're rarely modifying any of those core files, so any of those changes that are going to come up are going to be suspicious. To get around both of these drawbacks, we're seeing bad actors combine the two. So client side snippets of JavaScript are sending stolen credit card data to server side scripts that they've installed on the same server as the site. Now, this allows bad actors to cover their tracks a little bit because the traffic that's being redirected is going to the same server, and that's less likely to be flagged as suspicious. It's a bit more complicated to pull this off, but our team has been seeing this hybrid approach in the wild, so it's something to be on the lookout for. Now, another month has passed, and we found more cross site scripting attacks targeting WordPress plugins. Most notably, we discovered one that affects users of the YITH WooCommerce Ajax Product Filter plugin. Now, this is a plugin that allows WooCommerce stores to be filtered by product type, and it's pretty popular. It's got about 100,000 users right now, so with it being vulnerable, it's very important that all of them update to the latest version, which is 3.11.1. Some of the other plugins we found cross site scripting vulnerabilities with included Elementor Page Builder, Careerfy, JobSearch, and Newspaper. If you're looking for a full list of vulnerabilities that have been patched this month, John Castro at the Sucuri Labs blog has you covered. Check out our show notes for the link. Also, this month I had a blog go up detailing what's called a jibberish hack. It's basically the same motivation as an SEO spam attack where bad actors use your site's good standing to redirect visitors to their own sites. But in this attack, you'll find a bunch of randomly named folders filled with a ton of HTML files with really nonsensical file names like cheap-cool-hairstyles-photos.html. It's just going to be a mishmash of keywords that clearly you didn't put there. Unfortunately, just deleting all those HTML files and folders is not going to be enough to get rid of that jibberish hack though. You're going to need to fully clean any hacked files and database tables, and then you're going to have to deal with all the damage caused to your site's standing. And just keep in mind, if you find anything about that process too daunting, we're always here to help. Now, for this month's Sit Down, we have Sucuri analyst Krasimir Konov. Earlier in June, he had written a lab's note about a malicious downloader script that used the curl function, and we chatted a bit about it, but more importantly, we went really in-depth on all the different varieties of malware that website owners need to be aware of. But, before I get started with Krasimir, I just wanted to remind you about the Sucuri Sync-Up, our sister podcast. It's a weekly website security news briefing that you can find anywhere you get your podcasts, as well as the video version on our social media feed, and now you can even get it on your Amazon Alexa smart speakers. Just search Amazon skills for Sucuri Sync-Up, add the flash briefing, and get new content delivered every Monday. Now, on with the show. Hi Krasimir, thanks for joining us on the show. I thought we could start off and maybe have you tell us a little bit about yourself and what you do here at Sucuri? Krasimir Konov: Yeah, sure. Well, I joined Sucuri originally in 2014, but I've been in the IT business for about 10 years. Nine of those I did security. And currently at Sucuri I'm one of the malware analysts. I used to work in the front lines, used to clean websites and whatnot, and then I gradually moved up, and now I'm working in the malware research department. And my day to day job is basically analyzing malware, and then once I analyze it and figure out what it is, then I will create a signature for it. And we'll add those signatures to our tools, so we can automate some of the work we do. And I also write some Labs Notes blog posts. Usually, if I find something interesting in malware or some security topic, I'll write about it. Justin Channell: Yeah. And of those topics recently that you wrote about, one was about a malicious curl downloader, and how exactly did that work? Krasimir Konov: Right, yeah. That was an interesting one, but not very unique or anything like that. We see that a lot with curl being used as a downloader. It's a very common malware. So rather than including the actual malware in the file, the attackers would use curl to download the malicious code. In this case, they'll download it from Pastebin, but it could be anything. It could be another website or anything like that, and curl would just make a call to the website, request the code. The website will respond with the code, and then later on, there is some code to either save the output somewhere on the website, or you'll just run it through eval and execute the actual code right away. Justin Channell: Right. And you said that it's commonly found in malware, but let's kind of maybe talk a bit broader about malware in general. What is everything that is classified as malware? Krasimir Konov: Well, in general it will be anything that the owner of the website didn't authorize, anything that was added by a third party. There is a lot of different malware. It could be even something like a defacement that will also be considered malware because it was something the user did not authorize. Even though it might not be doing anything malicious on the website, it's not infecting users, the visit is still something they did not authorize. So defacement would also be considered malware. And even something like ransomware where the website is technically not really damaged, it's all encrypted, but it's not infecting anybody. It's not doing anything malicious, but it's still encrypting the entire website and asking the user or the customer, the owner of the website for a ransom they need to pay in order to get the website back online. Justin Channell: Okay. Let's maybe break it down to each individual type of malware. For example, what would be a way that maybe I-frames could be maliciously used by a hacker? Krasimir Konov: Yeah. An I-frame can be used maliciously when it loads content from another location. You can look at the I-frame as a window that just opens another website. So anything that website has on it, you're pretty much loading it through the I-frame. So if that website is infected and it's serving some kind of malware, by opening an I-frame, you're loading all those elements, everything that was on this website. And sometimes the I-frame can be as small as pixel or something hidden somewhere off the screen, so you wouldn't even know that it was opening it. Justin Channell: And yeah, I feel like we've also seen a lot of them where they're used almost to mimic popups as well. Krasimir Konov: Yeah. I mean the I-frame, it could just load from another website and the other website could do anything. It could be serving just malware and it would try to infect the user that doesn't even know that they're being connected to the other website. It could just have some other JavaScript that's just trying to open up pop ups on the original website through the I-frame. Yeah, it could be a lot of things. Justin Channell: Okay. And also, let's talk a little bit about conditional redirects and how those work. What allows a script to detect which devices are coming in and where they're coming from? Krasimir Konov: Right. Yeah. That's a common one we see a lot. Basically, a conditional redirect would be something, it's a redirect on the website. It's obviously malicious, but there's certain conditions that need to be met before the redirect is actually executed or the redirect happens. For example, let's say if it's on a phishing website or a phishing page that is hidden somewhere on the website. For example, if Google visits it, obviously the attacker doesn't want Google to see the actual phishing page and record it as a phishing page. So they'll look for, for example, the IP address. They would look for the user agent. And a lot of times they can tell that it's a bot. So they'll just return a 404 response, for example, that will be like, "Oh, page not found." So Google would be like, "Oh, it looks like this page doesn't exist." But then if a regular user goes to the same page, then those conditions will be met. The actual website or the script behind the phishing will check and see, and be like, "Oh, this one is running Firefox or Chrome," and be like, okay. And then they'll look at the IP and be like, "Oh, he's in whatever, he's in United States somewhere." And he's like, "Oh, okay. That's good." And then once all of these conditions are met, then the actual script will serve them the actual phishing page. And it'll be like, "Oh, you need to fill out this to recover your account or whatever, or type in your credentials to log in here." Justin Channell: And so this is the type of thing we're really, a website owner is going to run into this more commonly when people are complaining about they're getting served bad content or whatever, and they can't seem to replicate it. It's likely probably these kind of redirects. Is that right? Krasimir Konov: Right, right. It could be something as specific as, for example, a range of IP addresses that correspond to an ISP or maybe let's say a country. It could be like, "Oh, were targeting only customers in the US," so if you're connecting from another country and you go to the same website or the same page, it would just say 404. It will give you a page not found. But then if you actually have an IP address from the United States, you're connecting from the United States, then it will actually show you the phishing page. Justin Channell: Now another type of malware I feel like we see a lot here is SEO spam. We hear people talking about that. What are some of the top SEO spam keywords that you see coming through? Krasimir Konov: Yeah. We get that a lot. We see a lot of spam on websites. A lot of times attackers will use SEO spam to gain ranking for their own website. Or they'll just try to include some kind of SEO spam in links to another website that they're currently running or something. I mean, these things change all the time. So a website might be up for a week and then it'll disappear, and then they'll start another campaign. But yeah, we see that a lot. We see all kinds of keywords they use. Most common ones will be something like Viagra. We'll have like jerseys for sale. A lot of times, they'll use name brands like Nike, Rolex, Prada. We've seen even some essay writing services for some reason. I'm not sure why, but that's common. We see, for example, pharmaceuticals a lot that will use specific medicine names. They'll use all kinds of replicas, like a replica bag of this, replica this, replica that. We'd see prescription, also payday loans. And obviously there's some adult related sites and things like that keywords. Justin Channell: So pretty much anything that people are going to be searching and clicking on are probably going to be targets for SEO spam? Krasimir Konov: Right. I think a lot of it commonly is pharma related because a lot of people are looking to buy medicine online, and a lot of times will require a prescription. So a lot of people are like, "Oh, let me see if I can find this medicine that I can buy it online somewhere." They don't need a prescription. They don't want to pay to visit a doctor and whatnot, and they'll look for it. And yeah. Justin Channell: Now, whenever somebody's website does get hacked with a SEO spam attack, what kind of effect can it have on the website beyond just being defaced? Krasimir Konov: Yeah. You can have a lot of things can happen, negative things. For example, the website can be blacklisted because of the keywords. And that usually represents a big red warning when you go on the website, depending on who blacklisted it. But if it's Google, for example, you'll see a big warning and it'll tell you this website contains malware or there's something wrong with this website. So, pretty much all the traffic on the website will be gone. And then you can also lose a lot of your reputation if there is a SEO spam on the website. For example, if you were ranked in say number five for certain keywords that represent your product on Google search engines, and then suddenly you get hit with SEO spam, then all these search engines then go and visit the website. And all of a sudden they're like, "Oh, there's all these weird key words on here, all this SEO spam that's causing a lot of mixed signals." And the search engines are like, "Oh, where do we rank this website now? Do we rank them with this product that's originally what the website is about? Or do we take into consideration all these other keywords that are mixed up that are SEO spam?" So, all of a sudden your website might go from being ranked number five on the first page to being on the 10th page. And then you rank for all these other keywords that you didn't intend to. And then people search for something completely different. They're searching for jerseys or something, or now they're searching for Prada products, and then suddenly your website pops up in there. So you're not really getting any good traffic, not targeted traffic. But, yeah. Justin Channell: Okay. So in a lot of ways, the effects of SEO spam would kind of be the same for defacements or any kind of malware with the blacklisting, but it does bring that kind of unique part to it where then it can also then bring traffic that you weren't expecting from somebody searching for jerseys, for example. I had not really ever thought about that. Krasimir Konov: Right, right. Yeah. It will definitely bring some traffic. I've seen a lot of times where websites will be connected. Let's say, there was 1,000 websites that were all infected with SEO spam, and it will kind of link each other to try to bring each other up into the rankings. And so you would see a lot of strange traffic from some random websites that were, for example, that were previously infected, even if they might not be anymore. But yeah, they'll be sending traffic to you or there'll be usually search engines sending you traffic, but for the wrong keywords. People are looking for something else, so obviously they're not going to be interested in your website. They're not going to buy anything because they're not looking for that. Justin Channell: And now, so thinking of the way websites get infected, a very common way it seems to be is through phishing campaigns. What are some recommendations you have for the best ways to avoid becoming a phishing victim? Krasimir Konov: Yeah. There is some ways. I mean, it depends really on the type of attack. Obviously, a lot of people, when they think of phishing, they think, "Oh, it's just like a PayPal phishing page and it just looks like the original," but it could be more subtle. If it's just a regular page where you're just going and you get redirected to another website, obviously the first thing to look is if you have the security padlocks, make sure that traffic is encrypted. A lot of these websites don't really have any encryption nowadays. More are starting to get that with pre SSLs being issued and whatnot. But that's the first thing to look and see, make sure. Anywhere you're typing your sensitive information, you want to make sure you have the padlock to make sure everything is encrypted. Krasimir Konov: But also you want to look at the URL of the actual website you're visiting. A lot of times they'll try to hide it. So you might have to be careful and look closely. Something that might be an I will be an L or something like that. And a capital I and L might look kind of similar into your IRL, so you might miss something like that. Say, if you're looking for PayPal and it might replace the L with an I, and if you don't look closely, it might look exactly the same. And you're like, "Oh, okay, it's paypal.com," but not really. So yeah. Just pay attention to the URL, make sure it is the actual website. There's no paypal.com dot something, dot something else, dot com. Yeah. You want it to just say paypal.com, and then it'll have forward slash and something else. But yeah, it gets more complicated when you have, for example, a phishing page that's injected into a regular page. For example, you have a checkout page on a website that you're buying things from and you go through the checkout page and you're looking at where you type in your credit card information and whatnot. And you might have a phishing page that actually looks exactly like a little box that gives you where you put in your credit card number, or your name, your address, and all that. So that will be more subtle. For example, that could be also an I-frame that's just coming from another page. And it will look exactly like it's part of the website. You're on the legitimate website, but only that portion of the website is actually the phishing page. And you look at it and you're like, "Oh, okay. It looks fine. I'm just putting my credentials." So that one could be a lot harder to figure it out. Usually, if it's something like that, I look for something that looks kind of out of place. Maybe they didn't get the right font. It might not be the same as the original website or there might be something out of place, some fields that are missing or some fields that are squished into the left or the right. It looks kind of awkward. It's like, why would this be like this? The whole website looks professional. There's a pink background or something, for example, and then suddenly there's this white box in the middle. It's like, ah, it looks kind of weird, out of place. Justin Channell: So pretty much if anything looks slightly out of place, you really should double check everything at that point. Krasimir Konov: Right. Right. Yeah. Obviously there's more ways that you can check, but I wouldn't get into more technical, like inspecting elements and looking at stuff, but yeah. Justin Channell: And now another type of malware that's kind of, and it kind of plays in with whatever the other infection is, is backdoors. Can you give us some examples of what backdoors can be? It's mainly just when a hacker can get back into the site to reinfect it, but I know there are a ton of different methods. And what are some of the more common ones and then maybe some that really interesting that you've seen? Krasimir Konov: Yeah, there is a lot. They'll probably be one of the first things the hacker would do is if they compromise a website, obviously they'll try to spread backdoors and just inject code everywhere so they can get back in, even if the owner of the website or webmaster cleans it. They want to try and hide some malicious code somewhere so they can always get back in. There's many variations. A backdoor could be something as simple as a single line of code to just [inaudible 00:20:19] argument, some kind of string or something via get or post. Krasimir Konov: And then it runs into an eval, so it evaluates the code and executes it. And some backdoors are very complex and they can be included in, let's say you have a WordPress site and you have a specific login page where all the login credentials are being processed and everything else. They could even inject code into that to basically bypass the whole login mechanism so that they can just bypass everything. They don't even have to know any user. They don't have to know the password, nothing. They'll just include some lines in there, and every time they'll be just able to log in. Yeah. It gets pretty crazy. Yeah. I mean, there's all kinds of malware. There is always a malware, for example, that just targets credit cards and will just target the eCommerce websites. And they'll just try to steal the login credentials, I mean, the credit cards. They'll try to get your address, your credit card information, any kind of CVV code or whatever you typed into the billing address, everything. And then there's also malware like the backdoors that are just trying to keep the attacker in control and trying to get them back into the website. There's just so many variations of what a malicious user might want to do on a website. Some can be something as simple as just reinfecting the website. They don't want to keep control. They just want to keep reinfecting it with some kind of malware. So even if you clean it, it would just get reinfected. Some of them in the database, otherwise might be in the files. We've seen some added into a [inaudible 00:22:14] job that just keeps running on the server. There could be malware that is just a giant to, for example, attack out of websites. Like for example, a distributed denial service where they put the same malware on thousands of websites. And then they try to send traffic to one website to try to bring it down. Yeah. People try to do all kinds of stuff with websites. We've seen even some cryptocurrency mining malware that you go onto a website and suddenly your PC starts running like crazy. And you're like, what the hell is going on? Your fans turn on and the PC is 100% CPU. And it turns out that the website has some malware that's just by mining Bitcoins with your CPU and it's using all of it. Justin Channell: Wow. Okay. So one question now, the last question I have is of all the malware that you've seen, what do you think is the coolest piece of malware that you've ever seen? Krasimir Konov: I think the coolest would be the ones that are so subtle that you don't even know that it's there. For example, we've seen some that were pretty innovative. It will be just a one liner code that's just one line. And for example, it will be let's say 40-50 characters, something like that. And that's all it is. And they'll hide it somewhere in between the legitimate code. And if you don't know what you're looking for, you would never see it. It doesn't look suspicious. There is no links to some other website. There's no some kind of encrypted code or anything like that. It's just a simple one line. And then if you're just scrolling through the file looking for something, you would never see it. It just looks like all the other code. And then if you look closely, you're like, "Oh, there's this..." Look closely, and you're like, "Oh wow, this is not supposed to be there." And then you keep looking at it and you're like, "This looks really weird." And then you see that it's actually doing some malicious things and trying to evaluate some code or taking output from the outside, I mean, some input from outside, you can call it and give it code to run. Justin Channell: Well, Krasimir, thanks for coming on and talking to us for today. Krasimir Konov: Yeah. Thank you. Thank you. I'm so happy. I'm glad I was able to do this podcast and I can't wait to do another one. Justin Channell: Yeah, we'll have you on again. Thanks. Krasimir Konov: Thank you. Justin Channell: Thanks again to Krasimir for joining us here on the Sit Down. We'll be back with another episode next month. So be sure to subscribe on Apple podcasts, Spotify, Stitcher, or any podcasting platform. Also, be sure to follow us on social media at Sucuri Security and check us out at sucuri.net. That's S-U-C-U-R-I.net. I'm Justin Channell, And this has been the Sucuri Sit Down. Stay safe out there.](https://blog.sucuri.net/wp-content/uploads/2020/05/20-sucuri-podcast-blog-post_blog_image-390x183.jpg)
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