tommydeeee / yara-x

Experimenting with YARA and Rust

YARA-X

YARA-X is a re-incarnation of YARA, a pattern matching tool designed with malware researchers in mind. This new incarnation intends to be faster, safer and more user-friendly than its predecessor. The ultimate goal of YARA-X is to serve as the future replacement for YARA.

With YARA-X you can create descriptions of malware families (or whatever you want to describe) based on textual or binary patterns. Each description (a.k.a. rule) consists of a set of patterns and a boolean expression which determine its logic. Let’s see an example:

rule silent_banker : banker {
    meta:
        description = "This is just an example"
        threat_level = 3
        in_the_wild = true

    strings:
        $a = {6A 40 68 00 30 00 00 6A 14 8D 91}
        $b = {8D 4D B0 2B C1 83 C0 27 99 6A 4E 59 F7 F9}
        $c = "UVODFRYSIHLNWPEJXQZAKCBGMT"

    condition:
        $a or $b or $c
}

The above rule is telling YARA-X that any file containing one of the three patterns must be reported as silent_banker. This is just a simple example, more complex and powerful rules can be created by using wild-cards, case-insensitive strings, regular expressions, special operators and many other features that you'll find explained in the documentation.

FAQ

How does YARA-X compare to YARA?

Read this.

Which are the differences at the rule level?

Read this.

Is YARA still maintained?

Yes, it is. YARA is still being maintained, and future releases will include bug fixes and minor features. However, don’t expect new large features or modules. All efforts to enhance YARA, including the addition of new modules, will now focus on YARA-X.

What's the current state of YARA-X?

YARA-X is still in beta, but is mature and stable enough for use, specially from the command-line interface or one-shot Python scripts. While the APIs may still undergo minor changes, the foundational aspects are already established.

At VirusTotal, we have been running YARA-X alongside YARA for a while, scanning millions of files with tens of thousands of rules, and addressing discrepancies between the two. This means that YARA-X is already battle-tested. These tests have even uncovered YARA bugs!

Please test YARA-X and don’t hesitate to open an issue if you find a bug or some feature that you want to see implemented.