Fortiguard Bypass

[Roxine Denison]

youwould have to access the FortiGate for that with a reasonable admin account and change the web filtering policy (or DNS filter, if that is in place). If you have no access, that will be difficult or impossible to bypass. That is probably the intention of the network admin.

Perhaps you could talk to your college's IT department so that they will allow you to use these? Moreover, I am also a technical college student and not long ago I discovered StudyMoose for myself, more concretely, I came across this source -essays/medical-billing-and-coding which inspired me a lot, because here I found a very interesting information, there it talked about medical billing and coding, it really attracted me and I was amazed by what I read there.

The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.

NSE4 trainee here. Just trying to understand the functional real world difference between Allow and Exempt in the Web Filter. I understand that Allow continues through the remainder of the security profiles such as AV, IPS, Fortiguard web filtering etc whereas Exempt passes any further security inspection.

What I don't understand is a situation where allow would actually do anything compared to exempt. In my experience, when a client requests for a URL to be whitelisted, the URL is already blocked by Fortiguard. When I select "Allow", it goes through normal "Web Filtering", which it passes due to the allow rule, but then is blocked by Fortiguard web filtering. When I select "Exempt", it passes through Fortiguard Web Filtering and any remaining security filters.

What is the use case for the "Allow" rule? When would the rule actually allow traffic? What else would be blocking the web traffic except for the Fortiguard web filter? Also, it's annoying that there's no inbetween - either bypass nothing or bypass Fortiguard web filter and every other security profile.

Allow: Traffic is oassed to remaining operations, includin FortiGuard web filter, web content filter, web scripts filters and av scanning.

Exempt: Allow traffic from tusted sources to BYPASS all security inspections

My question was relating to the allow rule's functionality. What is the use case for allow? When would "allow" actually allow something past the web filter without it then hitting the fortiguard web filter and being blocked?

FortiGuard Labs observed "Critical" level of attack attempts to exploit an Authentication Bypass Vulnerability in TBK DVR devices (4104/4216) with upto more than 50,000+ unique IPS detections in the month of April 2023. The 5-year-old vulnerability (CVE-2018-9995) is due to an error when handling a maliciously crafted HTTP cookie. A remote attacker may be able to exploit this flaw to bypass authentication and obtain administrative privileges eventually leading access to camera video feeds. Learn More

TBK Vision is a video surveillance company which provides network CCTV devices and other related equipment such as DVRs for the protection of critical infrastructure facilities. According to the vendor website, they have over 600,000 Cameras and 50,000 Recorders installed all over the world in multiple sectors such as Banking, Retail, Government etc. According to the NIST NVD database, TBK DVR4104 and DVR4216 devices are also rebranded and sold as other brands such as Novo, CeNova, QSee, Pulnix, XVR 5 in 1, Securus, Night OWL, DVR Login, HVR Login, and MDVR. Another notable spike to mention is IPS detections related to MVPower CCTV DVR models (CVE-2016-20016) also known as JAWS webserver RCE. Previously seen to be exploited in the wild through 2017 and on-going. See additional resources for more information.

May 1, 2023: With tens of thousands of TBK DVRs available under different brands, publicly-available PoC code, and an easy-to-exploit makes this vulnerability an easy target for attackers. The recent spike in IPS detections shows that network camera devices remain a popular target for attackers.

FortiGuard Labs is not aware of any patches provided by the vendor and recommends organizations to review installed models of CCTV camera systems and related equipment for vulnerable models.

This may be considered a dupe of my previously asked question but, My ISP uses the software Fortinet to block web content through URL filtering. I'm curious if anyone knows how to bypass this. Fortinet consistently blocks some educational material on accident because the URLs are thrown into a massive pool.

From the Fortinet Wikipedia page: "Fortinet is an American multinational corporation headquartered in Sunnyvale, California. It develops and markets cybersecurity software and appliances and services, such as firewalls, anti-virus, intrusion prevention and endpoint security. Fortinet was founded in 2000 by brothers Ken and Michael Xie."For context.

Before we start, we will all need a basic understanding of how UAC works. UAC is an access control feature introduced with Microsoft Windows Vista and Windows Server 2008 (and is included in pretty much all Windows versions after that). The main intent of UAC is to make sure applications are limited to standard user privileges. If a user requires an increase in access privileges, the administrator of the device (usually the owner) needs to authorize that change by actively selecting a prompt-based query. We all should be familiar with this user experience.

The goal for this feature was that it would limit accidental system changes and malware from compromising a system, since elevating privilege required an additional user intervention to verify that this change is what the user was intending to do, and that only trusted apps would receive admin privileges.

The UAC feature seems like a good measure for preventing malware from compromising a system. But unfortunately, it turns out that criminals have discovered how to bypass the UAC feature, many of which that are pretty trivial. Many of them work on the specific configuration setting of UAC. Below are a few examples of UAC bypass techniques that have been built into the opensource Metasploit tool to help you test your systems.

The COM handler bypass is similar, as it references specific registry (COM hander) entries that can be created and then referenced when a high integrity process is loaded. On a side note, if you want to see which executables can auto-elevate, try using the strings program which is part of sysinternals:

Over the years, our FortiGuard Labs team has discovered many threats that include a bypass UAC technique. A great example is a threat we discovered a few years back that contained the Fareit malware. A Fareit payload typically includes stealing credentials and downloading other payloads. This particular campaign run was delivered via a phishing email containing a malicious macro that called a PowerShell script to download a file named sick.exe. This seems like a typical attack strategy, but to execute the sick.exe payload it used the high integrity (auto-elevated) eventvwr.exe to bypass the UAC consent prompt. Below is the PowerShell script.

You can see that the first part of the script downloads the malicious file using the (New-object System.net.webclient).Downloadfile() method we discussed in the first blog in this series. The second part of the script adds an entry to the registry using the command reg add HKCU\Software\Classes\mscfile\shell\open\command /d %tmp%\sick.exe /f.

Finally, the last command in the script runs the eventvwr.exe, which needs to run MMC. As I discussed earlier, the exe has to query both the HKCU\Software\Classes\mscfile\shell\open\command\ and HKCR\mscfile\shell\open\command\. When it does so, it will find sick.exe as an entry and will execute that instead of the MMC.

A recent technique we detected and blocked was a newer version of Trickbot. When this payload runs it tries to execute the WSReset UAC Bypass technique to circumvent the UAC prompt. Once again, it leverages an executable that has higher integrity (and higher privilege) and has the autoElevate property enabled. This specific bypass works on Windows 10. If the payload encounters Windows 7, it will instead use the CMSTPUA UAC bypass technique. In Figure 5 you can see our FortiEDR forensic technology identify the reg.exe trying to modify the registry value with DelegateExecute.

Our FortiSIEM customers can take advantage of rules to detect some of these UAC bypass techniques. Below is an example rule to detect a UAC bypass using the Windows backup tool sdclt.exe and the Eventvwr version we mentioned before.

As I mentioned earlier, Metasploit has a few bypass UAC techniques you can leverage. Remember that in the attack chain your adversary already has an initial foothold on the box, and they are trying to get around UAC. With that said, you should already have a meterpreter session running on your test box. Executing the steps to run a bypass UAC (using fodhelper) technique is pretty simple.

Once again, we continue play the cat and mouse game. As an industry we build protections (in this case UAC) and eventually the adversary finds ways around them. This will most likely not change. So the important task is understanding your strengths and weaknesses against these real-world attacks. If you struggle with keeping up to date with all of this, you can always turn to your consulting partner or vendor to make sure you have the right security controls and services in place to keep up with the latest threats, and that you are also able to address the risk and identify malicious activities using such tools as EDR, MDR, UEBA and SIEM technologies.

I will close this blog like I did last time. As you go through the process of testing each Bypass UAC attack technique, it is important to not only understand the technique, but also be able to simulate it. Then, monitor your security controls, evaluate if any gaps exist, and document and make improvements needed for coverage.

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