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

Application JA4+ Fingerprints Chrome JA4=t13d1516h2_8daaf6152771_02713d6af862 (TCP)
JA4=q13d0312h3_55b375c5d22e_06cda9e17597 (QUIC)
JA4=t13d1517h2_8daaf6152771_b0da82dd1658 (pre-shared key)
JA4=t13d1517h2_8daaf6152771_b1ff8ab2d16f (no key) IcedID Malware Dropper JA4H=ge11cn020000_9ed1ff1f7b03_cd8dafe26982 IcedID Malware JA4=t13d201100_2b729b4bf6f3_9e7b989ebec8
JA4S=t120300_c030_5e2616a54c73 Sliver Malware JA4=t13d190900_9dc949149365_97f8aa674fd9
JA4S=t130200_1301_a56c5b993250
JA4X=000000000000_4f24da86fad6_bf0f0589fc03
JA4X=000000000000_7c32fa18c13e_bf0f0589fc03 Cobalt Strike JA4H=ge11cn060000_4e59edc1297a_4da5efaf0cbd
JA4X=2166164053c1_2166164053c1_30d204a01551 SoftEther VPN JA4=t13d880900_fcb5b95cb75a_b0d3b4ac2a14 (client)
JA4S=t130200_1302_a56c5b993250
JA4X=d55f458d5a6c_d55f458d5a6c_0fc8c171b6ae Qakbot JA4X=2bab15409345_af684594efb4_000000000000 Pikabot JA4X=1a59268f55e5_1a59268f55e5_795797892f9c Darkgate JA4H=po10nn060000_cdb958d032b0 LummaC2 JA4H=po11nn050000_d253db9d024b Evilginx JA4=t13d191000_9dc949149365_e7c285222651 Reverse SSH Shell JA4SSH=c76s76_c71s59_c0s70 Windows 10 JA4T=64240_2-1-3-1-1-4_1460_8 Epson Printer JA4TScan=28960_2-4-8-1-3_1460_3_1-4-8-16

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 FilesWiresharkthsark.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).

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.

Download Ja4