Handler on Duty: Jan Kopriva
Threat Level: green
Podcast Detail
SANS Stormcast Wednesday, August 6th, 2025: Machinekeys and VIEWSTATEs; Perplexity Unethical Learning; SonicWall Updates
If you are not able to play the podcast using the player below: Use this direct link to the audio file: https://traffic.libsyn.com/securitypodcast/9558.mp3
My Next Class
Application Security: Securing Web Apps, APIs, and Microservices | Las Vegas | Sep 22nd - Sep 27th 2025 |
Application Security: Securing Web Apps, APIs, and Microservices | Denver | Oct 4th - Oct 9th 2025 |
Stealing Machinekeys for fun and profit (or riding the SharePoint wave)
Bojan explains in detail how .NET uses Machine Keys to protect the VIEWSTATE, and how to abuse the VIEWSTATE for code execution if the Machine Keys are lost.
https://isc.sans.edu/diary/Stealing%20Machine%20Keys%20for%20fun%20and%20profit%20%28or%20riding%20the%20SharePoint%20wave%29/32174
Perplexity is using stealth, undeclared crawlers to evade website no-crawl directives
Perplexity will change its User Agent, or use different originating IP addresses, if it detects being blocked from scanning websites
https://blog.cloudflare.com/perplexity-is-using-stealth-undeclared-crawlers-to-evade-website-no-crawl-directives/
Gen 7 SonicWall Firewalls – SSLVPN Recent Threat Activity
Over the past 72 hours, there has been a notable increase in both internally and externally reported cyber incidents involving Gen 7 SonicWall firewalls where SSLVPN is enabled.
https://www.sonicwall.com/support/notices/gen-7-sonicwall-firewalls-sslvpn-recent-threat-activity/250804095336430
Application Security: Securing Web Apps, APIs, and Microservices | Las Vegas | Sep 22nd - Sep 27th 2025 |
Application Security: Securing Web Apps, APIs, and Microservices | Denver | Oct 4th - Oct 9th 2025 |
Application Security: Securing Web Apps, APIs, and Microservices | Dallas | Dec 1st - Dec 6th 2025 |
Podcast Transcript
Hello and welcome to the Wednesday, August 6, 2025 edition of the SANS Internet Storm Center's Stormcast. My name is Johannes Ullrich, recording today from Jacksonville, Florida. And this episode is brought to you by the SANS.edu Graduate Certificate Program in Penetration Testing and Ethical Hacking. Last week when we talked about SharePoint, one of the things that kept coming up was the VIEWSTATE. The VIEWSTATE is how .NET applications kind of maintain state. In forms, you'll typically see that VIEWSTATE being included as a blob. Now, whenever we send something to the user like this, you of course have to protect its integrity. And that's part of where the Machinekey comes in, where the data is digitally signed or protected with Mac. Now, the other option is that you can also encrypt the data if, for example, you have some sensitive data that's included as part of that VIEWSTATE. But the real problem with SharePoint was that the exploit did allow access to the Machinekeys that are used to basically create the integrity protection. Without that protection, an attacker -speak user is able to create malicious VIEWSTATEs that, when deserialized on the server, can lead to arbitrary code execution. And that's exactly what Boyan is walking you through here, how the VIEWSTATE is being used and how it can be app used. The VIEWSTATE is either stored in your web.config file or in the registry. However, if you have multiple servers that, for example, share a load, then you must store it in the web .config file because all the servers must use the same VIEWSTATE. So they're essentially compatible with each other. If one of them creates a view state, the other server is able to read it. But what this means is if an attacker is able to read web.config, well, they then have also remote code execution on the server. Boyan is going over a couple of locations where the view state may be found. And with that also, you know, scripts and such that can be used to still take advantage of it. YSO-serial.net is sort of the tool of choice to create malicious objects for embedding in the VIEWSTATE that can then be used to actually launch any kind of attack. And as Boyan here demonstrates with a little sample application, it can easily then lead once the view state is generated to remote code execution. Like in this particular case to a remote shell. It's a very detailed diary. If you're particularly into penetration testing, let's just try to better understand from a defensive point as well what's up with the VIEWSTATE, what's up with these Machinekeys we talked so much about last week. This is really sort of a very thorough and detailed walkthrough of what this really all means. And I keep saying there are two kinds of AI and LLM companies. Those that observe intellectual properties and those that will fail. Latest example here, Perplexity. Perplexity apparently is modifying its user agents to bypass any protections that websites put in place to specifically do not allow Perplexity to spider their content for machine learning. Cloudflare documented this here in their blog post. Essentially, what's happening with Perplexity is that they will initially use their public and normal user agent that identifies them as Perplexity. It's Perplexity user. Now, if they run into any problems, let's say that robots.txt protects the site from not being spidered by Perplexity user. Or you have a web application firewall. Well, in that case, they will actually modify their user agent and then still try to access the site. They'll also try to connect from different IP addresses. So essentially do whatever an attacker would do to bypass some filters like web application firewalls. Robot.txt is specifically designed to be used by well -behaved and ethical search engines that are spidering the site. If you're looking, for example, at the internetstormcentersrobot.txt file, we exclude a couple of pages that are just too dynamic and don't really provide much value for a search engine. On the other hand, would cost us some effort to actually produce those pages. And that's exactly what's happening now with Perplexity where their aggressive spidering could actually cause damage like denial of service attacks. We have seen things like this before, not just from Perplexity, but I think it was last year we saw and we still see this actually occasionally where OpenAI is hitting our honeypots with basically attack URLs. WordPress attacks and the like that are coming from OpenAI's network from systems that identify themselves as basically part of their cluster of systems that is spidering the web for content to be included in learning. So I guess AI now learns from our honeypots. Well, a couple of days ago, I reported about findings from Arctic Wolf that they see compromises of SonicWolf firewalls that may be taking advantage of so far unknown vulnerability. Well, we now have a little bit confirmation that at least something strange is going on here. Google Mandiant Huntress saw similar attacks and there is now an official statement from SonicWolf about this, as they call it, ongoing investigation. Still no confirmation that there is an actual survey. So it's still possible that these are backdoors or something left behind by prior exploits. But they did come up here with some recommended mitigation steps. And number one here is to disable the SL VPN services. Of course, that may not be practical as they also state here. If that's why you have this particular device, maybe you can restrict access to the SL VPN component to trusted source IP addresses. So that may be sort of the second best thing to do. The other options they have here is just the basic best practice, things like multi -factor authentication or such. But the Arctic Wolf write-up specifically stated that some of the compromised devices they have seen had multi-factor authentication enabled. So that's not necessarily going to keep you safe here. It's just adding an additional barrier likely for an attacker to overcome. Well, and that's it for today. So thanks for listening. Thanks for subscribing and liking this podcast. Thanks for recommending it. And as always, special thanks for leaving any good comments in your favorite podcast platform. Thanks and talk to you again tomorrow. Bye.