Tag Archives: Security

YARA-X 1.11.0 Release: Hash Function Warnings, (Sun, Jan 11th)

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YARA-X's 1.11.0 release brings a new feature: hash function warnings.

When you write a YARA rule to match a cryptographic hash (either the full file content or a part of it), what's actually going on are string comparisons:

Function hash.sha256 returns a string (the hexadecimal SHA256 hash it calculated) and that is compared to a literal string that is the hash you want to find.

If you make a mistake in your literal string hash (for example: unintentionally add an extra space), then the match will fail.

But YARA-X will now show a warning like this:

Another example is where you mixup hashes: you provide a SHA1 literal string hash, and it should be a SHA256.

 

Didier Stevens
Senior handler
blog.DidierStevens.com

(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.

Analysis using Gephi with DShield Sensor Data, (Wed, Jan 7th)

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I'm always looking for new ways of manipulating the data captured by my DShield sensor [1]. This time I used Gephi [2] and Graphiz [3] a popular and powerful tool for visualizing and exploring relationships between nodes, to examine the relationship between the source IP, filename and which sensor got a copy of the file. I queried the past 30 days of data stored in my ELK [4] database in Kibana using ES|QL [5][6] to query and export the data and import the result into Gephi. 

Tool Review: Tailsnitch, (Tue, Jan 6th)

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In yesterday's podcast, I mentioned "tailsnitch", a new tool to audit Tailscale configurations. Tailscale is an easy-to-use overlay to Wireguard. It is probably best compared to STUN servers in VoIP in that it allows devices behind NAT to connect directly to each other. Tailscale just helps negotiate the setup, and once the connection is established, data will flow directly between the connected devices. I personally use it to provide remote assistance to family members, and it has worked great for this purpose. Tailscale uses a "Freemium" model. For my use case, I do not need to pay, but if you have multiple users or a large number of devices, you may need to pay a monthly fee. There are also a few features that are only available to paid accounts.

Risks of OOB Access via IP KVM Devices, (Mon, Jan 5th)

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Recently, a new "breed" of IP-based KVM devices has been released. In the past, IP-based KVM devices required dedicated "server-grade" hardware using IPMI. They often cost several $100 per server, and are only available for specific systems that support the respective add-on cards. These cards are usually used to provide "Lights Out" access to servers, allowing a complete reboot and interaction with the pre-boot environment via simple web-based tools. In some cases, these IPMI tools can also be used via various enterprise/data center management tools.

Debugging DNS response times with tshark, (Fri, Jan 2nd)

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One of my holiday projects was to redo and optimize part of my home network. One of my homelab servers failed in November. I had only thrown the replacement in the rack to get going, but some cleanup was needed. In addition, a lot of other "layer 1" issues had to be fixed by re-crimping some network drops and doing general network hygiene. The dust buny kind hygiene, not so much the critical controls type. After all, I don't want things to overheat, and it is nice to see all network links syncing properly.

Positive trends related to public IP ranges from the year 2025, (Thu, Dec 18th)

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Since the end of the year is quickly approaching, it is undoubtedly a good time to look back at what the past twelve months have brought to us… And given that the entire cyber security profession is about protecting various systems from “bad things” (and we’ve all correspondingly seen more than our share of the “bad”), I thought that it might be pleasant to look at a few positive background trends that have accompanied us throughout the year, without us necessarily noticing…