Want new ideas for your brim images? Check out these 7 creative brim images for instant inspiration now.

So, I’ve been meaning to really dig into what Brim can do with images, you know, the stuff you might find floating around in network traffic. Heard some folks talking about “brim images” and figured it was high time I gave it a whirl myself. It’s always good to get your hands dirty with these tools rather than just reading about them, right?

My First Steps – Just Diving In

First thing, I got Brim up and running on my machine. Had a couple of packet capture files, those .pcap things, lying around from some old tests. I specifically picked one I suspected might have some JPEGs or PNGs flying back and forth from some web browsing I did a while back. You never know what you’ll find in that old data, it’s like a digital attic sometimes.

So, I dragged one of these PCAPs into Brim. It took a moment to chomp through it; Brim does its thing processing it with Zeek logs and all that jazz in the background. My initial thought was, okay, where do images even show up? It’s not like there’s a big shiny button that says “Show Me The Pictures!” I wish it were that simple sometimes.

Figuring Out the How-To

I started by just poking around the different log types Brim shows you from Zeek. The seemed like the most logical place to start, as most web images come over HTTP. I was scanning through the columns, looking for things like content types – you know, stuff like image/jpeg or image/png. And bingo, I found some entries that looked promising.

Then I remembered Brim has this pretty powerful search feature, using ZQL. It’s not always the most intuitive thing for me, but I’m getting better. So, I tried to cobble together a query. Something along the lines of _path="http" AND mime_type=="image/jpeg". That definitely helped narrow things down a bit. It showed me the log entries for JPEG images, but not the images themselves, not directly anyway.

This is where it got a bit fiddly, and I spent some time scratching my head. Brim doesn’t just, like, pop up all the images in a neat little gallery. That would be too easy, I guess! What I started to understand was that Zeek, which Brim uses under the hood, has the capability to extract files from the network traffic. If Zeek is configured to do that, and it successfully extracts an image, then Brim can help you find the metadata about that extracted file. Sometimes, depending on your setup and if the file extraction was successful during the PCAP import, you might find paths to where those files are stored on your system, or at least IDs you can use to manually find them if your Zeek is configured to dump them somewhere specific.

I then shifted my focus to the “Files” view within Brim. This seemed like the place to be. If Zeek actually managed to carve out the image files during the PCAP processing, they should theoretically show up there. And indeed, I saw some entries! For a few of them, Brim would even show a little thumbnail preview if it could! That was pretty neat when it worked, a little “aha!” moment. But it wasn’t always a sure thing, mind you. Sometimes you just get the file info – name, type, size – and you’d have to go grab the actual file from your Zeek extraction directory if you really wanted to open it and see the full image. So, not a fully integrated image browser, but definitely a pointer.

What I Learned and My Thoughts

So, after spending a good chunk of the afternoon on this, here’s what I sort of landed on regarding “brim images.” Brim itself isn’t primarily an image viewer in the way you’d think of a photo gallery application. It’s much more about helping you find the evidence and metadata of images that transited your network, leveraging Zeek’s file extraction capabilities.

• You need data with actual images: Seems obvious, I know, but if your PCAP is all just DNS queries and SSH traffic, you’re not going to magically find JPEGs.
• Zeek’s file extraction is crucial: This is the backbone. If Zeek isn’t extracting files, or isn’t configured to extract the types of images you’re looking for, Brim won’t have much to show you image-wise beyond the basic log entries mentioning a mime type.
• Queries are your best friend: Getting comfortable with ZQL to filter for MIME types (e.g., mime_type:"image/" to get all image types) or even filenames (if you happen to know them) is super helpful. I found tx_hosts and rx_hosts useful too, to see where images were coming from or going to.
• The “Files” view is where the (potential) visual is: That’s your best bet for seeing if Brim (via Zeek) actually pulled out the images. Sometimes you get those handy previews, sometimes it’s just the metadata, which is still valuable.

It wasn’t as straightforward as just typing “show all images,” but once I got the hang of how Brim and Zeek work together for file analysis, it started to make a lot more sense. It’s definitely more of a forensic or network analysis tool in this regard, helping you identify and locate image files that passed through the network, rather than a casual image browser. You’ll likely still need other tools to view all the extracted images properly if Brim doesn’t show a preview or if you need to do deeper analysis on the image files themselves.

So yeah, that was my little adventure into the practical side of finding images using Brim. It’s definitely a useful capability if you’re doing network forensics or just curious about what kinds of files are being transferred. Just gotta know where to look and how to ask Brim the right questions with its query language. Definitely learned a thing or two, and that’s always a good day. Now, if only it could make me a coffee too, then it’d be perfect…