Bug #6634
closed
tls: Invalid ja3 due to double client hello
Added by Eric Leblond 11 months ago.
Updated about 2 months ago.
Description
Stamus Networks team has discovered some weird TLS connections happening in real networks. These connections are not respecting the TLS RFCs as the client sends 2 hello messages (one in TLS 1.2 and the other one in TLS v1.3) but the server does not care and answer any way.
The result is surprising as the ja_string ends up to compose of 9 commas separated elements and as a result the ja3 hash is not computed on one or the other of the hello message.
- Affected Versions 7.0.1 added
- Affected Versions deleted (
7.0.0)
Can you share a pcap / SV test for this?
Can confirm we are seeing exactly this problem on approx 0.005% of TLS sessions
I am also seeing a case where only two fields are being output, this also seems invalid: "771,4865-4866-4867-49195-49199-49196-49200-52393-52392-49171-49172-156-157-47-53"
And another discrepancy, which I am not sure about and investigating a bit more is that, sometimes the EVE JSON reports "TLS 1.3", but both ja3-strings are saying 771 (TLS 1.2). Not sure why this is.
- Related to Bug #7016: tls: hello retry request handling issues added
- Subject changed from Invalid ja3 due to double client hello to tls: Invalid ja3 due to double client hello
Gianni Tedesco wrote in #note-5:
I am also seeing a case where only two fields are being output, this also seems invalid: "771,4865-4866-4867-49195-49199-49196-49200-52393-52392-49171-49172-156-157-47-53"
I can see one path where it happens :
Do you have TLS_DECODER_EVENT_HANDSHAKE_INVALID_LENGTH in these cases @Giuseppe Longo ?
- Status changed from In Progress to In Review
- Assignee changed from Eric Leblond to Philippe Antoine
- Target version changed from TBD to 8.0.0-beta1
- Label Needs backport to 7.0 added
- Label deleted (
Needs backport to 7.0)
- Status changed from In Review to Resolved
- Status changed from Resolved to Closed
- Related to Bug #7256: ja3: Error: ja3: Buffer should not be NULL added
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