TLS ClientHello (JA4)

t13d1517h2_8daaf6152771_68c5a8c2958d

first seen 2026-07-02 09:17 · last seen 2026-08-02 09:57 · JSON

Inconsistencies

User-Agents observed with this fingerprint that contradict what it proves at the wire. all inconsistencies →

fingerprint User-Agent claims wire shows confidence seen first seen last seen

t13d1517h2_8daaf6152771_68c5a8c2958d

Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/…

User-Agent claims Firefox 145.0

TLS extensions or signature algorithms differ from every measured Firefox capture

The cipher suites match Firefox, but the extension set or signature algorithms differ from every capture even after normalizing handshake-variant extensions. Most likely a field-trial, ECH, or build variant the catalog has not captured; occasionally mimicry. This sharpens as catalog coverage grows.

Full User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/20100101 Firefox/145.0
Claimed version	145.0
Measured versions	146.0.1, 152.0.1, 154.0, 140.0.2, 151.0.4, 151.0.2, 139.0, 153.0.1, 155.0, 152.0.5, 153.0.3, 142.0.1, 153.0.4, 152.0.6, 150.0.2, 135.0, 132.0, 152.0.3, 148.0.2, 137.0, 141.0, 155.0.1, 153.0, 151.0.3, 144.0.2, 154.0.1, 134.0, 152.0.4, 151.0
Layer	cipher suites match; extension set or signature algorithms differ
JA4 label	unlabeled

low

2026-07-02

t13d1517h2_8daaf6152771_68c5a8c2958d

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:154…

User-Agent claims Firefox 154.0

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:154.0) Gecko/20100101 Firefox/154.0
Claimed version	154.0
Measured versions	146.0.1, 152.0.1, 154.0, 140.0.2, 151.0.4, 151.0.2, 139.0, 153.0.1, 155.0, 152.0.5, 153.0.3, 142.0.1, 153.0.4, 152.0.6, 150.0.2, 135.0, 132.0, 152.0.3, 148.0.2, 137.0, 141.0, 155.0.1, 153.0, 151.0.3, 144.0.2, 154.0.1, 134.0, 152.0.4, 151.0
Layer	cipher suites match; extension set or signature algorithms differ
JA4 label	unlabeled

low

2026-07-08

t13d1517h2_8daaf6152771_68c5a8c2958d

Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv…

User-Agent claims Firefox 154.0

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:154.0) Gecko/20100101 Firefox/154.0
Claimed version	154.0
Measured versions	146.0.1, 152.0.1, 154.0, 140.0.2, 151.0.4, 151.0.2, 139.0, 153.0.1, 155.0, 152.0.5, 153.0.3, 142.0.1, 153.0.4, 152.0.6, 150.0.2, 135.0, 132.0, 152.0.3, 148.0.2, 137.0, 141.0, 155.0.1, 153.0, 151.0.3, 144.0.2, 154.0.1, 134.0, 152.0.4, 151.0
Layer	cipher suites match; extension set or signature algorithms differ
JA4 label	unlabeled

low

2026-08-02

Decomposed attributes

Protocol	`t (TLS over TCP)`
TLS version	`13`
SNI	`d (domain)`
Cipher count	`15`
Extension count	`17`
ALPN	`h2`
Ciphers	`002f, 0035, 009c, 009d, 1301, 1302, 1303, c013, c014, c02b, c02c, c02f, c030, cca8, cca9`
Extensions	`0005, 000a, 000b, 000d, 0012, 0017, 001b, 001c, 0022, 0023, 002b, 002d, 0033, fe0d, ff01`
Signature algorithms	`0403, 0503, 0603, 0804, 0805, 0806, 0401, 0501, 0601, 0201`
JA4_r	`t13d1517h2_002f,0035,009c,009d,1301,1302,1303,c013,c014,c02b,c02c,c02f,c030,cca8,cca9_0005,000a,000b,000d,0012,0017,001b,001c,0022,0023,002b,002d,0033,fe0d,ff01_0403,0503,0603,0804,0805,0806,0401,0501,0601,0201`
JA4_o (sample)	`t13d1517h2_77608d807651_02cb82eae503`
JA4_ro (sample)	`t13d1517h2_1301,1303,1302,c02b,c02f,cca9,cca8,c02c,c030,c013,c014,009c,009d,002f,0035_0000,0017,ff01,000a,000b,0023,0010,0005,0022,0012,0033,002b,000d,002d,001c,001b,fe0d_0403,0503,0603,0804,0805,0806,0401,0501,0601,0201`

Co-observed signals

Signals from other families seen in the same observation. A fingerprint spread thinly across many lower-layer signatures is a classic inconsistency signal.

HTTP request (JA4H)

fingerprint	co-occurrences
`ge20nr11enus_b83bdc73d8bd_000000000000_000000000000`	1
`ge20nr14dech_3bfc33496497_000000000000_000000000000`	1
`ge20nr13dech_bd497514d847_000000000000_000000000000`	1
`ge20nr11frfr_187a9385d229_000000000000_000000000000`	1

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`1:65536;2:0;4:131072;5:16384\|12517377\|3:0:0:42\|m,p,a,s` Match?Exact match in Thumbprint's published controlled catalog captures: firefox 154.0, firefox 152.0.5, firefox 152.0.1, +3 more.The fingerprint page shows the full measured match list. More on the catalog.	2
`1:65536;2:0;4:131072;5:16384\|12517377\|3:0:0:22\|m,p,a,s` Match?Exact match in Thumbprint's published controlled catalog captures: firefox 153.0, firefox 153.0.3, firefox 154.0, +25 more.The fingerprint page shows the full measured match list. More on the catalog.	2

TCP SYN (p0f)

fingerprint	co-occurrences
`4:40+24:0:1460:mss*44,10:mss,sok,ts,nop,ws:df,id+:0`	2
`4:51+13:0:1380:65535,13:mss,sok,ts,nop,ws:df,id+:0`	1
`4:51+13:0:1452:65535,6:mss,nop,ws,nop,nop,ts,sok,eol+1:df,ecn:0`	1

TCP SYN (JA4T)

fingerprint	co-occurrences
`64240_2-4-8-1-3_1460_10`	2
`65535_2-4-8-1-3_1380_13`	1
`65535_2-1-3-1-1-8-4-0-0_1452_6`	1

User-Agent

fingerprint	co-occurrences
`Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/20100101 Firefox/145.0`	2
`Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:154.0) Gecko/20100101 Firefox/154.0`	1
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:154.0) Gecko/20100101 Firefox/154.0`	1

Country

fingerprint	co-occurrences
`CH` · Switzerland	2
`FR` · France	1
`ES` · Spain	1

Network (ASN)

fingerprint	co-occurrences
`AS13030` · Init7 (Switzerland) Ltd.	2
`AS13335` · Cloudflare, Inc.	1
`AS3352` · TELEFONICA DE ESPANA S.A.U.	1

Cross-transport links

TLS ClientHello fingerprints observed from the same client via the beacon's correlation id on the other transport (e.g. this stack over TCP ↔ that stack over QUIC).

fingerprint	linked observations
`q13d0315h3_55b375c5d22e_dc5437974b47`	2