[Zeek] SSH auth_success state true set, but admin claims no logins

[Jim Mellander]

Since Zeek only sees the encrypted traffic of an ssh session, it can only
make a best-guess based on packet-size analysis, which is not necessarily
going to be 100% accurate.

On Mon, Sep 16, 2019 at 11:24 AM Collyer, Jeffrey W (jwc3f) <
jwc3f at virginia.edu> wrote:

> So recently I saw an SSH login to a device from outside the US.  I
> reported it to the end system admin.  The Zeek log set the auth_success
> state to true, but the admin of the box claims no successful login and is
> pushing back that it is a false positive.
>
> Have other Zeek users ever seen this?  Is the SSH auth state detection
> mistaken here?
> I don’t have pcaps to verify one way to the other, sadly.
>
>
> {"_path":"ssh","_system_name":"corelight","_write_ts":"2019-09-12T22:26:32.106142Z","ts":"2019-09-12T22:26:31.226136Z","uid":"C95i0o2Jl77LXHb2R9","id.orig_h”:”x.x.x.x","id.orig_p":49670,"id.resp_h”:”x.x.x.x","id.resp_p":22,"version":2,"auth_success":true,"auth_attempts":1,"direction":"INBOUND","client":"SSH-2.0-OpenSSH_7.2p2
> Ubuntu-4ubuntu2.4","server":"SSH-2.0-OpenSSH_7.4","cipher_alg":"
> chacha20-poly1305 at openssh.com","mac_alg":"umac-64-etm at openssh.com
> ","compression_alg":"none","kex_alg":"curve25519-sha256 at libssh.org
> ","host_key_alg":"ecdsa-sha2-nistp256","host_key":"68:1e:68:89:5e:e5:20:72:f7:e6:bf:21:de:07:3a:b1”}
>
> Can anyone shed light on this?
>
> Thanks
> Jeff
>
>
> Jeffrey Collyer
> Information Security Engineer
> University of Virginia
> jwc3f at virginia.edu
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> zeek at zeek.org
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