samba - May 2017 - Windows 10 spawning thousands of child processes on Samba 4.3.11 server

On Tue, 23 May 2017 08:44:42 +0200
"L.P.H. van Belle via samba" <samba at lists.samba.org> wrote:
> Did you TV/Radio broke??  ;-) 
> 
> This really smells like some malware/cryptoware. 
> Seen this ones on a network, and that was a cypto trying to write to
> shares. And they to that really really fast. 
> 
> Increast the samba debug logs and track if this is client related. 
> That where i would start. 
> 
They were my thoughts, the connections are from guest by the look of
them and removing 'map to guest = Bad User' would reset it to 'map
to
guest = Never' and the connections would be dropped.

I think the OP needs to start looking at their clients ;-)

Rowland

On Tue, May 23, 2017 at 8:59 AM, Rowland Penny via samba <
samba at lists.samba.org> wrote:
> On Tue, 23 May 2017 08:44:42 +0200
> "L.P.H. van Belle via samba" <samba at lists.samba.org>
wrote:
>
> > Did you TV/Radio broke??  ;-)
> >
> > This really smells like some malware/cryptoware.
> > Seen this ones on a network, and that was a cypto trying to write to
> > shares. And they to that really really fast.
> >
> > Increast the samba debug logs and track if this is client related.
> > That where i would start.
> >
>
> They were my thoughts, the connections are from guest by the look of
> them and removing 'map to guest = Bad User' would reset it to
'map to
> guest = Never' and the connections would be dropped.
>
> I think the OP needs to start looking at their clients ;-)
>
> Rowland
>
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>
Alrite,
I doubt there is malware running. The nobody/nogroup processes are created
when running certain applications.

I've upped the log level to 3 and see some interesting stuff from Windows
client "WIN8-13" where Admin user is logged in and accessing
applications
on the Samba share. Server IP is 10.10.1.6, servername "india". The
share
is mounted with username "production" which is in smbpasswd:

root# pdbedit -w -L
production:1001:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:43DEDBC664EA95353348102454C3BD:[U
         ]:LCT-5923EA2E:
administration:1002:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:4FF63806DDD0952F97B03608A7FDC4:[U
         ]:LCT-5923EA5E:

Here is a log snippet:

[2017/05/23 10:51:59.104021,  3]
../source3/smbd/service.c:774(make_connection_snum)
  win8-13 (ipv4:10.10.1.63:51224) connect to service IPC$ initially as user
production (uid=1001, gid=1001) (pid 1686)
[2017/05/23 10:51:59.104487,  3]
../source3/smbd/msdfs.c:993(get_referred_path)
  get_referred_path: |administration| in dfs path \10.10.1.6\administration
is not a dfs root.
[2017/05/23 10:51:59.105493,  3] ../source3/smbd/dir.c:628(dptr_create)
  creating new dirptr 0 for path appl/SubScr, expect_close = 0
.
.
.
[2017/05/23 10:51:59.130743,  3]
../source3/param/loadparm.c:1600(lp_add_ipc)
  adding IPC service
[2017/05/23 10:51:59.130814,  3]
../source3/auth/auth.c:178(auth_check_ntlm_password)
  check_ntlm_password:  Checking password for unmapped user []\[]@[WIN8-13]
with the new password interface
[2017/05/23 10:51:59.130866,  3]
../source3/auth/auth.c:181(auth_check_ntlm_password)
  check_ntlm_password:  mapped user is: [INDIA]\[]@[WIN8-13]
[2017/05/23 10:51:59.130928,  3]
../source3/auth/auth.c:249(auth_check_ntlm_password)
  check_ntlm_password: guest authentication for user [] succeeded
[2017/05/23 10:51:59.132111,  3]
../auth/ntlmssp/ntlmssp_util.c:69(debug_ntlmssp_flags)
  Got NTLMSSP neg_flags=0xe2088297
[2017/05/23 10:51:59.132715,  3]
../auth/ntlmssp/ntlmssp_server.c:452(ntlmssp_server_preauth)
  Got user=[] domain=[] workstation=[WIN8-13] len1=1 len2=0
[2017/05/23 10:51:59.132798,  3]
../source3/param/loadparm.c:3754(lp_load_ex)
  lp_load_ex: refreshing parameters

I wonder why this guest unmapped user appears?

Thanks.

On Tue, 23 May 2017 14:13:33 +0200
Asbjorn Taugbol via samba <samba at lists.samba.org> wrote:
> 
> I wonder why this guest unmapped user appears?
> 
Probably because you have 'map to guest = bad user', this is from
'man
smb.conf':

Bad User - Means user logins with an invalid password are
rejected, unless the username does not exist, in which case it
is treated as a guest login and mapped into the guest
account.

Or to put it another way, ANYBODY can connect!

Rowland