JA3 Fingerprint
O que é JA3 Fingerprint?
JA3 FingerprintA TLS client fingerprinting method by John Althouse, Jeff Atkinson, and Josh Atkins (Salesforce, 2017) that hashes the ordered TLS ClientHello parameters into a 32-character MD5 — used to identify and group TLS clients without inspecting payload.
JA3 is a TLS client fingerprinting technique published by John Althouse, Jeff Atkinson, and Josh Atkins of Salesforce in 2017. It hashes a deterministic, ordered string of the TLS ClientHello's negotiation parameters — TLS version, accepted ciphers, extensions, elliptic curves, and elliptic-curve point formats — into a 32-character MD5 string. Because most clients (browsers, libraries, malware C2 implants) produce a stable, library-specific ClientHello, JA3 hashes group traffic by client implementation regardless of destination, certificate, or SNI. A companion JA3S hashes the server's ServerHello. JA3 has been used widely to detect malware C2 channels whose Go/curl/Python TLS libraries produce distinctive hashes that differ from typical browsers, to fingerprint scanners and tools (Nmap, Burp, Cobalt Strike default profiles), and to enable TLS inventory without packet decryption. Modern weaknesses are well known: attackers can mimic browser ClientHellos with libraries such as utls; JA3 hashes can collide across genuinely different clients. JA4 (2023) and its variants address several JA3 limitations.
● Exemplos
- 01
A SOC sees a JA3 hash matching a known Cobalt Strike default malleable profile on an internal endpoint, kicking off an IR investigation.
- 02
A passive TLS inventory groups traffic by JA3 to estimate the share of corporate traffic still using outdated OpenSSL versions.
● Perguntas frequentes
O que é JA3 Fingerprint?
A TLS client fingerprinting method by John Althouse, Jeff Atkinson, and Josh Atkins (Salesforce, 2017) that hashes the ordered TLS ClientHello parameters into a 32-character MD5 — used to identify and group TLS clients without inspecting payload. Pertence à categoria Segurança de rede da cibersegurança.
O que significa JA3 Fingerprint?
A TLS client fingerprinting method by John Althouse, Jeff Atkinson, and Josh Atkins (Salesforce, 2017) that hashes the ordered TLS ClientHello parameters into a 32-character MD5 — used to identify and group TLS clients without inspecting payload.
Como funciona JA3 Fingerprint?
JA3 is a TLS client fingerprinting technique published by John Althouse, Jeff Atkinson, and Josh Atkins of Salesforce in 2017. It hashes a deterministic, ordered string of the TLS ClientHello's negotiation parameters — TLS version, accepted ciphers, extensions, elliptic curves, and elliptic-curve point formats — into a 32-character MD5 string. Because most clients (browsers, libraries, malware C2 implants) produce a stable, library-specific ClientHello, JA3 hashes group traffic by client implementation regardless of destination, certificate, or SNI. A companion JA3S hashes the server's ServerHello. JA3 has been used widely to detect malware C2 channels whose Go/curl/Python TLS libraries produce distinctive hashes that differ from typical browsers, to fingerprint scanners and tools (Nmap, Burp, Cobalt Strike default profiles), and to enable TLS inventory without packet decryption. Modern weaknesses are well known: attackers can mimic browser ClientHellos with libraries such as utls; JA3 hashes can collide across genuinely different clients. JA4 (2023) and its variants address several JA3 limitations.
Como se defender contra JA3 Fingerprint?
As defesas contra JA3 Fingerprint costumam combinar controles técnicos e práticas operacionais, conforme detalhado na definição acima.
Quais são outros nomes para JA3 Fingerprint?
Nomes alternativos comuns: JA3, JA3 hash.
● Termos relacionados
- network-security№ 629
JA4 Fingerprint
A 2023 successor to JA3, published by John Althouse at FoxIO, that produces structured, human-readable TLS, HTTP, SSH, and TCP fingerprints designed to remain robust as TLS clients evolve and to be paired across protocols.
- network-security№ 1280
Handshake TLS
Troca inicial do protocolo Transport Layer Security que autentica o servidor (e opcionalmente o cliente) e deriva as chaves simetricas que cifram o restante da sessao.
- network-security№ 1279
TLS (Transport Layer Security)
Protocolo criptográfico padronizado pelo IETF que fornece confidencialidade, integridade e autenticação ao tráfego entre duas aplicações em rede.
- cryptography№ 190
Suíte criptográfica
Combinação nomeada de algoritmos criptográficos — troca de chaves, autenticação, cifragem e integridade — negociada por protocolos como o TLS para uma dada sessão.
- defense-ops№ 338
Engenharia de detecao
Disciplina de desenhar, testar, implantar e manter detecoes de seguranca como codigo, com cobertura mensuravel das tecnicas adversarias.
- network-security№ 326
Inspeção Profunda de Pacotes (DPI)
Técnica de inspeção que examina todo o payload dos pacotes de rede — não apenas os cabeçalhos — para identificar aplicações, conteúdo e ameaças.