JA4+ - Suite Of Network Fingerprinting Standards

JA4+ is a suite of network Fingerprinting methods that are easy to use and easy to share. These methods are both human and machine readable to facilitate more effective threat-hunting and analysis. The use-cases for these fingerprints include scanning for threat actors, malware detection, session hijacking prevention, compliance automation, location tracking, DDoS detection, grouping of threat actors, reverse shell detection, and many more.

Please read our blogs for details on how JA4+ works, why it works, and examples of what can be detected/prevented with it:
JA4+ Network Fingerprinting (JA4/S/H/L/X/SSH)
JA4T: TCP Fingerprinting (JA4T/TS/TScan)

To understand how to read JA4+ fingerprints, see Technical Details

This repo includes JA4+ Python, Rust, Zeek and C, as a Wireshark plugin.

JA4/JA4+ support is being added to:
GreyNoise
Hunt
Driftnet
DarkSail
Arkime
GoLang (JA4X)
Suricata
Wireshark
Zeek
nzyme
Netresec's CapLoader
NetworkMiner">Netresec's NetworkMiner
NGINX
F5 BIG-IP
nfdump
ntop's ntopng
ntop's nDPI
Team Cymru
NetQuest
Censys
Exploit.org's Netryx
cloudflare.com/bots/concepts/ja3-ja4-fingerprint/">Cloudflare
fastly
with more to be announced...

Examples

For more, see ja4plus-mapping.csv
The mapping file is unlicensed and free to use. Feel free to do a pull request with any JA4+ data you find.

Plugins

Wireshark
Zeek
Arkime

Binaries

Recommended to have tshark version 4.0.6 or later for full functionality. See: https://pkgs.org/search/?q=tshark

Download the latest JA4 binaries from: Releases.

JA4+ on Ubuntu

sudo apt install tshark
./ja4 [options] [pcap]

JA4+ on Mac

1) Install Wireshark https://www.wireshark.org/download.html which will install tshark 2) Add tshark to $PATH

ln -s /Applications/Wireshark.app/Contents/MacOS/tshark /usr/local/bin/tshark
./ja4 [options] [pcap]

JA4+ on Windows

1) Install Wireshark for Windows from https://www.wireshark.org/download.html which will install tshark.exe
tshark.exe is at the location where wireshark is installed, for example: C:\Program Files\Wireshark\thsark.exe
2) Add the location of tshark to your "PATH" environment variable in Windows.
(System properties > Environment Variables... > Edit Path)
3) Open cmd, navigate the ja4 folder

ja4 [options] [pcap]

Database

An official JA4+ database of fingerprints, associated applications and recommended detection logic is in the process of being built.

In the meantime, see ja4plus-mapping.csv

Feel free to do a pull request with any JA4+ data you find.

JA4+ Details

JA4+ is a set of simple yet powerful network fingerprints for multiple protocols that are both human and machine readable, facilitating improved threat-hunting and security analysis. If you are unfamiliar with network fingerprinting, I encourage you to read my blogs releasing JA3 here, JARM here, and this excellent blog by Fastly on the State of TLS Fingerprinting which outlines the history of the aforementioned along with their problems. JA4+ brings dedicated support, keeping the methods up-to-date as the industry changes.

All JA4+ fingerprints have an a_b_c format, delimiting the different sections that make up the fingerprint. This allows for hunting and detection utilizing just ab or ac or c only. If one wanted to just do analysis on incoming cookies into their app, they would look at JA4H_c only. This new locality-preserving format facilitates deeper and richer analysis while remaining simple, easy to use, and allowing for extensibility.

For example; GreyNoise is an internet listener that identifies internet scanners and is implementing JA4+ into their product. They have an actor who scans the internet with a constantly changing single TLS cipher. This generates a massive amount of completely different JA3 fingerprints but with JA4, only the b part of the JA4 fingerprint changes, parts a and c remain the same. As such, GreyNoise can track the actor by looking at the JA4_ac fingerprint (joining a+c, dropping b).

Current methods and implementation details:
| Full Name | Short Name | Description | |---|---|---| | JA4 | JA4 | TLS Client Fingerprinting
| JA4Server | JA4S | TLS Server Response / Session Fingerprinting | JA4HTTP | JA4H | HTTP Client Fingerprinting | JA4Latency | JA4L | Latency Measurment / Light Distance | JA4X509 | JA4X | X509 TLS Certificate Fingerprinting | JA4SSH | JA4SSH | SSH Traffic Fingerprinting | JA4TCP | JA4T | TCP Client Fingerprinting | JA4TCPServer | JA4TS | TCP Server Response Fingerprinting | JA4TCPScan | JA4TScan | Active TCP Fingerprint Scanner

The full name or short name can be used interchangeably. Additional JA4+ methods are in the works...

To understand how to read JA4+ fingerprints, see Technical Details

Licensing

JA4: TLS Client Fingerprinting is open-source, BSD 3-Clause, same as JA3. FoxIO does not have patent claims and is not planning to pursue patent coverage for JA4 TLS Client Fingerprinting. This allows any company or tool currently utilizing JA3 to immediately upgrade to JA4 without delay.

JA4S, JA4L, JA4H, JA4X, JA4SSH, JA4T, JA4TScan and all future additions, (collectively referred to as JA4+) are licensed under the FoxIO License 1.1. This license is permissive for most use cases, including for academic and internal business purposes, but is not permissive for monetization. If, for example, a company would like to use JA4+ internally to help secure their own company, that is permitted. If, for example, a vendor would like to sell JA4+ fingerprinting as part of their product offering, they would need to request an OEM license from us.

All JA4+ methods are patent pending.
JA4+ is a trademark of FoxIO

JA4+ can and is being implemented into open source tools, see the License FAQ for details.

This licensing allows us to provide JA4+ to the world in a way that is open and immediately usable, but also provides us with a way to fund continued support, research into new methods, and the development of the upcoming JA4 Database. We want everyone to have the ability to utilize JA4+ and are happy to work with vendors and open source projects to help make that happen.

ja4plus-mapping.csv is not included in the above software licenses and is thereby a license-free file.

Q&A

Q: Why are you sorting the ciphers? Doesn't the ordering matter?
A: It does but in our research we've found that applications and libraries choose a unique cipher list more than unique ordering. This also reduces the effectiveness of "cipher stunting," a tactic of randomizing cipher ordering to prevent JA3 detection.

Q: Why are you sorting the extensions?
A: Earlier in 2023, Google updated Chromium browsers to randomize their extension ordering. Much like cipher stunting, this was a tactic to prevent JA3 detection and "make the TLS ecosystem more robust to changes." Google was worried server implementers would assume the Chrome fingerprint would never change and end up building logic around it, which would cause issues whenever Google went to update Chrome.

So I want to make this clear: JA4 fingerprints will change as application TLS libraries are updated, about once a year. Do not assume fingerprints will remain constant in an environment where applications are updated. In any case, sorting the extensions gets around this and adding in Signature Algorithms preserves uniqueness.

Q: Doesn't TLS 1.3 make fingerprinting TLS clients harder?
A: No, it makes it easier! Since TLS 1.3, clients have had a much larger set of extensions and even though TLS1.3 only supports a few ciphers, browsers and applications still support many more.

JA4+ was created by:

John Althouse, with feedback from:

Josh Atkins
Jeff Atkinson
Joshua Alexander
W.
Joe Martin
Ben Higgins
Andrew Morris
Chris Ueland
Ben Schofield
Matthias Vallentin
Valeriy Vorotyntsev
Timothy Noel
Gary Lipsky
And engineers working at GreyNoise, Hunt, Google, ExtraHop, F5, Driftnet and others.

Contact John Althouse at john@foxio.io for licensing and questions.

_{^{Copyright (c) 2024, FoxIO}}

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Skyhook - A Round-Trip Obfuscated HTTP File Transfer Setup Built To Bypass IDS Detections

Skyhook is a REST-driven utility used to smuggle files into and out of networks defended by IDS implementations. It comes with a pre-packaged web client that uses a blend of React, vanilla JS, and web assembly to manage file transfers.

Key Links

• Download here
• See the user documentation to get started

Features

• Round trip file content obfuscation
• User-configurable obfuscation chaining
• Self-signed and Lets Encrypt certificate procurement methods
• Embedded web applications for both configuration and file transfers.
• Server fingerprinting resiliency techniques:
  • Encrypted loaders capable of dynamically encrypting interface files as the file transfer interface is rendered
  • API and web resource path randomization

Brief Description

Note: See the user documentation for more thorough discussion of Skyhook and how it functions.

Skyhook's file transfer server seamlessly obfuscates file content with a user-configured series of obfuscation algorithms prior to writing the content to response bodies. Clients, which are configred with the same obfuscation algorithms, deobfuscate the file content prior to saving the file to disk. A file streaming technique is used to manage the HTTP transactions in a chunked manner, thus facilitating large file transfers.

flowchart

subgraph sg-cloudfront[Cloudfront CDN]
    cf-listener(443/tls)
end

subgraph sg-vps[VPS]
    subgraph sg-skyhook[Skyhook Servers]
        admin-listener(Admin Server<br>45000/tls)
        transfer-listener(Transfer Server<br>45001/tls)
    end

    config-file(Config File<br>/var/skyroot/config.yml)

    admin-listener -..->|Reads &<br>Manages| config-file

    webroot(Webroot<br>/var/skyhook/webroot)
    transfer-listener -..->|Serves From &<br>Writes Cleartext<br>Files To| webroot
end


    op-browser(Operator<br>Web Browser) -->|Administration<br>Traffic| admin-listener
    op-browser <-->|Obfuscated<br>Data| transfer-listener

subgraph sg-corp[Corporate Environment]
    subgraph sg-compromised[Beachhead Host]
        comp-browser(Web Browser) -->|Reads &<b   r>Writes| cleartext-file(Cleartext Files)
    end
end

comp-browser <-->|Obfuscated<br>Data| cf-listener <-->|Obfuscated<br>Data| transfer-listener

A Brief Example

For example, here is a working obfuscation configuration:

And here is the file transfer interface. Clicking "Download" results in the file being retrieved in chunks that are encrypted with the chain of obfuscation methods configured above.

JavaScript deobfuscates the file before prompting the user to save it to disk.

Below is a request stemming from a download being inspected with Burp. Key elements of the transaction are encrypted to evade detection.

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Fingerprintx - Standalone Utility For Service Discovery On Open Ports!

fingerprintx is a utility similar to httpx that also supports fingerprinting services like as RDP, SSH, MySQL, PostgreSQL, Kafka, etc. fingerprintx can be used alongside port scanners like Naabu to fingerprint a set of ports identified during a port scan. For example, an engineer may wish to scan an IP range and then rapidly fingerprint the service running on all the discovered ports.

Features

• Fast fingerprinting of exposed services
• Application layer service discovery
• Plays nicely with other command line tools
• Automatic metadata collection from identified services

Supported Protocols:

Installation

From Github

go install github.com/praetorian-inc/fingerprintx/cmd/fingerprintx@latest

From source (go version > 1.18)

$ git clone git@github.com:praetorian-inc/fingerprintx.git
$ cd fingerprintx

# with go version > 1.18
$ go build ./cmd/fingerprintx
$ ./fingerprintx -h

Docker

$ git clone git@github.com:praetorian-inc/fingerprintx.git
$ cd fingerprintx

# build
docker build -t fingerprintx .

# and run it
docker run --rm fingerprintx -h
docker run --rm fingerprintx -t praetorian.com:80 --json

Usage

fingerprintx -h

The -h option will display all of the supported flags for fingerprintx.

Usage:
  fingerprintx [flags]
TARGET SPECIFICATION:
	Requires a host and port number or ip and port number. The port is assumed to be open.
	HOST:PORT or IP:PORT
EXAMPLES:
	fingerprintx -t praetorian.com:80
	fingerprintx -l input-file.txt
	fingerprintx --json -t praetorian.com:80,127.0.0.1:8000

Flags:
      --csv               output format in csv
  -f, --fast              fast mode
  -h, --help              help for fingerprintx
      --json              output format in json
  -l, --list string       input file containing targets
  -o, --output string     output file
  -t, --targets strings   target or comma separated target list
  -w, --timeout int       timeout (milliseconds) (default 500)
  -U, --udp               run UDP plugins
  -v, --verbose           verbose mode

The fast mode will only attempt to fingerprint the default service associated with that port for each target. For example, if praetorian.com:8443 is the input, only the https plugin would be run. If https is not running on praetorian.com:8443, there will be NO output. Why do this? It's a quick way to fingerprint most of the services in a large list of hosts (think the 80/20 rule).

Running Fingerprintx

With one target:

$ fingerprintx -t 127.0.0.1:8000
http://127.0.0.1:8000

By default, the output is in the form: SERVICE://HOST:PORT. To get more detailed service output specify JSON with the --json flag:

$ fingerprintx -t 127.0.0.1:8000 --json
{"ip":"127.0.0.1","port":8000,"service":"http","transport":"tcp","metadata":{"responseHeaders":{"Content-Length":["1154"],"Content-Type":["text/html; charset=utf-8"],"Date":["Mon, 19 Sep 2022 18:23:18 GMT"],"Server":["SimpleHTTP/0.6 Python/3.10.6"]},"status":"200 OK","statusCode":200,"version":"SimpleHTTP/0.6 Python/3.10.6"}}

Pipe in output from another program (like naabu):

$ naabu 127.0.0.1 -silent 2>/dev/null | fingerprintx
http://127.0.0.1:8000
ftp://127.0.0.1:21

Run with an input file:

$ cat input.txt | fingerprintx
http://praetorian.com:80
telnet://telehack.com:23

# or if you prefer
$ fingerprintx -l input.txt
http://praetorian.com:80
telnet://telehack.com:23

With more metadata output: