TLS ClientHello (JA4)

t13d1513h2_8daaf6152771_748f4c70de1c

first seen 2026-07-23 18:58 · last seen 2026-08-18 14:15 · 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

t13d1513h2_8daaf6152771_748f4c70de1c

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137…

User-Agent claims Firefox 137.5

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 (Windows NT 10.0; Win64; x64; rv:137.5) Gecko/20100101 Firefox/137.5
Claimed version	137.5
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

2026-08-18

t13d1513h2_8daaf6152771_748f4c70de1c

Mozilla/5.0 (X11; Linux x86_64; rv:137.5) Gecko/…

User-Agent claims Firefox 137.5

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:137.5) Gecko/20100101 Firefox/137.5
Claimed version	137.5
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

2026-08-17

t13d1513h2_8daaf6152771_748f4c70de1c

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137…

User-Agent claims Firefox 137.3

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.3) Gecko/20100101 Firefox/137.3
Claimed version	137.3
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

2026-08-18

t13d1513h2_8daaf6152771_748f4c70de1c

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

User-Agent claims Firefox 137.2

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:137.2) Gecko/20100101 Firefox/137.2
Claimed version	137.2
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

2026-08-18

t13d1513h2_8daaf6152771_748f4c70de1c

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137…

User-Agent claims Firefox 137.6

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.6) Gecko/20100101 Firefox/137.6
Claimed version	137.6
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

2026-08-18

Distinct clients per day (last 30 days, peak 7/day)

Distinct clients are counted by IP-hash per complete UTC day — unlike observation counts this is insensitive to one chatty client, but NAT merges clients and address rotation splits them.

Decomposed attributes

Protocol	`t (TLS over TCP)`
TLS version	`13`
SNI	`d (domain)`
Cipher count	`15`
Extension count	`13`
ALPN	`h2`
Ciphers	`002f, 0035, 009c, 009d, 1301, 1302, 1303, c013, c014, c02b, c02c, c02f, c030, cca8, cca9`
Extensions	`0005, 000a, 000b, 000d, 0017, 001c, 0022, 002b, 0033, fe0d, ff01`
Signature algorithms	`0403, 0503, 0603, 0804, 0805, 0806, 0401, 0501, 0601, 0203, 0201`
JA4_r	`t13d1513h2_002f,0035,009c,009d,1301,1302,1303,c013,c014,c02b,c02c,c02f,c030,cca8,cca9_0005,000a,000b,000d,0017,001c,0022,002b,0033,fe0d,ff01_0403,0503,0603,0804,0805,0806,0401,0501,0601,0203,0201`
JA4_o (sample)	`t13d1513h2_77608d807651_b9d95c74ef12`
JA4_ro (sample)	`t13d1513h2_1301,1303,1302,c02b,c02f,cca9,cca8,c02c,c030,c013,c014,009c,009d,002f,0035_0000,0017,ff01,000a,000b,0010,0005,0022,0033,002b,000d,001c,fe0d_0403,0503,0603,0804,0805,0806,0401,0501,0601,0203,0201`

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
`ge20nn12enus_a72b71f519fc_000000000000_000000000000`	18

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`1:65536;2:0;4:131072;5:16384\|12517377\|1:0:0:42\|m,p,a,s`	11
`1:65536;2:0;4:131072;5:16384\|12517377\|1:0:0:256\|m,p,a,s`	7

TCP SYN (p0f)

fingerprint	co-occurrences
`6:47+17:0:1440:mss*45,7:mss,sok,ts,nop,ws:flow:0`	3
`6:55+9:0:1440:mss*45,7:mss,sok,ts,nop,ws:flow:0`	3
`4:54+10:0:1460:32768,10:mss,nop,ws,sok,ts::0`	3
`4:50+14:0:1460:32768,10:mss,nop,ws,sok,ts::0`	2
`4:50+14:0:1460:mss*44,7:mss,sok,ts,nop,ws:df,id+:0`	1
`4:54+10:0:1460:mss*44,7:mss,sok,ts,nop,ws:df,id+:0`	1
`4:47+17:0:1400:mss*44,7:mss,sok,ts,nop,ws:df,id+:0`	1
`4:50+14:0:1460:65535,9:mss,sok,ts,nop,ws:df,id+:0`	1
`4:46+18:0:1460:mss*44,9:mss,nop,nop,sok,nop,ws:df,id+:0`	1
`4:51+13:0:1460:32768,10:mss,nop,ws,sok,ts::0`	1

TCP SYN (JA4T)

fingerprint	co-occurrences
`64800_2-4-8-1-3_1440_7`	6
`32768_2-1-3-4-8_1460_10`	6
`64240_2-4-8-1-3_1460_7`	2
`65535_2-4-8-1-3_1460_9`	1
`64240_2-4-8-1-3_1400_7`	1
`64240_2-1-1-4-1-3_1460_9`	1
`42340_2-1-1-4-1-3_1460_11`	1

User-Agent

fingerprint	co-occurrences
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:128.0) Gecko/20100101 Firefox/128.0`	10
`Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.5) Gecko/20100101 Firefox/137.5`	2
`Mozilla/5.0 (X11; Linux x86_64; rv:125.5) Gecko/20100101 Firefox/125.5`	1
`Mozilla/5.0 (X11; Linux x86_64; rv:137.5) Gecko/20100101 Firefox/137.5`	1
`Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.3) Gecko/20100101 Firefox/137.3`	1
`Mozilla/5.0 (X11; Linux x86_64; rv:125.2) Gecko/20100101 Firefox/125.2`	1
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:137.2) Gecko/20100101 Firefox/137.2`	1
`Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.6) Gecko/20100101 Firefox/137.6`	1

Country

fingerprint	co-occurrences
`NL` · Netherlands	7
`SE` · Sweden	3
`FI` · Finland	3
`DE` · Germany	2
`US` · United States	1
`UA` · Ukraine	1
`AT` · Austria	1

Network (ASN)

fingerprint	co-occurrences
`AS215125` · Church of Cyberology	6
`AS24940` · Hetzner Online GmbH	3
`AS214379` · South Park Networks LLC	3
`AS60729` · Stiftung Erneuerbare Freiheit	2
`AS53667` · FranTech Solutions	1
`AS208323` · Foundation for Applied Privacy	1
`AS6698` · Virtual Systems LLC	1
`AS12989` · Black HOST Ltd	1