Snort mailing list archives

Re: missing pcaps for alerts


From: John Ives <jives () security berkeley edu>
Date: Thu, 21 Jun 2012 14:29:03 -0700

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I know its been 8 months, but I have been able to limp along using
2.9.1.0 (though my VRT subscription has been getting wasted for a
while), so I haven't pressed this issue, but its now reaching the
point where its becoming a real pain.

Additionally, in an effort to see if this was a FreeBSD specific
problem brought up a RHEL 6 box with a very basic snort installation
(configure; make; make install) and tried testing again with the
latest version but still get the same problem.  I have just added the
unified2 output to the snort.conf, and have seen some events (so far I
have found it with sid 1201) in just that last few minutes where the
packet appeared in the unified2 file and not in the pcap.

Any idea what is happening?

John

On 10/25/2011 2:05 PM, John Ives wrote:
Any word on when devel will be able look into this.  Unlike my
reading of Eoin's problem, the traffic doesn't appear in the
unified2 file either (I originally thought it did but upon further
investigation I am not seeing it in either the pcap or the unified2
files).

I have tried upgrading to 2.9.1.2 hoping that would fix the
problem. At this point I am probably going to need to revert to
2.9.1.0 (which worked) to get everything working properly.

Yours,

John

On 10/20/2011 10:50 AM, Joel Esler wrote:
Devel is going to look into this, however, they are busy with
two big things right now, and when they complete that, I'm sure
they'll chime in with some needs to test this out.

Thanks

-- Joel Esler Senior Research Engineer, VRT OpenSource Community 
Manager Sourcefire


On Oct 20, 2011, at 1:40 PM, Eoin Miller wrote:

Hey Joel,


I've been noticing this for a while but kept forgetting to get 
around to looking into it more in depth, I figured it was 
barnyard2 having an issue, but it does appear to be snorts 
logging output. If multiple alerts are firing on the same
frame, Snort doesn't seem to re-log the frame correctly for
multiple alerts:

If we have a test set of 3 rules like below: alert tcp any any
-> any any (msg:"MZ 1"; file_data; content:"MZ"; within:2;
sid:1; rev:1;) alert tcp any any -> any any (msg:"MZ 2";
file_data; content:"MZ"; within:2; sid:2; rev:1;) alert tcp any
any -> any any (msg:"MZ 3"; file_data; content:"MZ"; within:2;
sid:3; rev:1;)

Now we run them against a PCAP of a user downloading an 
executable file, it alerts 3 times as expected in our fast
alert output log. However, in the unified2 log, we have the
following at the beginning of the file when we run the
u2spewfoo binary against it:

---BEGIN--- (Event) sensor id: 0    event id: 1     event
second: 1319130108        event microsecond: 745191 sig id: 3
gen id: 1       revision: 1      classification: 0 priority: 0
ip source: 71.191.147.210       ip destination: 10.181.188.73
src port: 80    dest port: 64916        protocol: 6
impact_flag: 0 blocked: 0

Packet sensor id: 0    event id: 1     event second: 1319130108
 packet second: 1319130108       packet microsecond: 745191 
linktype: 1     packet_length: 1514 00 00 5E 00 01 02 00 10 DB
FF 26 00 08 00 45 00  ..^.......&...E. 05 DC 28 A0 40 00 38 06
71 EC 47 BF 93 D2 0A B5  ..(.@.8.q.G..... BC 49 00 50 FD 94 2E
8F 54 A2 FC 56 2E AC 50 10  .I.P....T..V..P. 00 6C C1 9A 00 00
48 54 54 50 2F 31 2E 31 20 32  .l....HTTP/1.1 2 30 30 20 4F 4B
0D 0A 44 61 74 65 3A 20 54 68 75  00 OK..Date: Thu 2C 20 32 30
20 4F 63 74 20 32 30 31 31 20 31 37  , 20 Oct 2011 17 3A 31 34
3A 30 39 20 47 4D 54 0D 0A 53 65 72 76  :14:09 GMT..Serv 65 72
3A 20 41 70 61 63 68 65 2F 32 2E 32 2E 31  er: Apache/2.2.1 34
20 28 55 62 75 6E 74 75 29 0D 0A 4C 61 73 74  4 (Ubuntu)..Last
2D 4D 6F 64 69 66 69 65 64 3A 20 54 68 75 2C 20  -Modified:
Thu, 31 38 20 41 75 67 20 32 30 31 31 20 30 30 3A 34  18 Aug
2011 00:4 32 3A 31 33 20 47 4D 54 0D 0A 45 54 61 67 3A 20  2:13
GMT..ETag: 22 31 38 36 36 30 33 2D 34 30 65 30 30 2D 34 61
"186603-40e00-4a 61 62 63 65 32 34 37 30 32 37 66 22 0D 0A 41
63  abce247027f"..Ac 63 65 70 74 2D 52 61 6E 67 65 73 3A 20 62
79 74  cept-Ranges: byt 65 73 0D 0A 43 6F 6E 74 65 6E 74 2D 4C
65 6E 67  es..Content-Leng 74 68 3A 20 32 36 35 37 32 38 0D 0A
4B 65 65 70  th: 265728..Keep 2D 41 6C 69 76 65 3A 20 74 69 6D
65 6F 75 74 3D  -Alive: timeout= 31 35 2C 20 6D 61 78 3D 31 30 
30 0D 0A 43 6F 6E  15, max=100..Con 6E 65 63 74 69 6F 6E 3A 20
4B 65 65 70 2D 41 6C  nection: Keep-Al 69 76 65 0D 0A 43 6F 6E
74 65 6E 74 2D 54 79 70  ive..Content-Typ 65 3A 20 61 70 70 6C
69 63 61 74 69 6F 6E 2F 78  e: application/x 2D 6D 73 64 6F 73
2D 70 72 6F 67 72 61 6D 0D 0A  -msdos-program.. 0D 0A 4D 5A 90
00 03 00 00 00 04 00 00 00 FF FF  ..MZ............ 00 00 B8 00
00 00 00 00 00 00 40 00 00 00 00 00  ..........@..... 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00  ................ 00 00
00 00 00 00 00 00 00 00 00 00 00 00 D8 00  ................ 00
00 0E 1F BA 0E 00 B4 09 CD 21 B8 01 4C CD 21  ..........!..L.!
54 68 69 73 20 70 72 6F 67 72 61 6D 20 63 61 6E  This program
can 6E 6F 74 20 62 65 20 72 75 6E 20 69 6E 20 44 4F  not be run
in DO 53 20 6D 6F 64 65 2E 0D 0D 0A 24 00 00 00 00 00  S
mode....$..... ---SNIP---



After this alert and packet, there are 11 more subsequent 
packets logged. However, the other two events have NO packets 
with them as we can see below from the end of the output:


---SNIP--- E0 8B 00 85 C0 74 02 FF D0 83 45 E0 04 EB E6 C7 
.....t....E..... 45 FC FE FF FF FF E8 20 00 00 E...... ..

(Event) sensor id: 0    event id: 2     event second:
1319130108 event microsecond: 745191 sig id: 2       gen id: 1 
revision: 1      classification: 0 priority: 0     ip source: 
71.191.147.210       ip destination: 10.181.188.73 src port:
80 dest port: 64916        protocol: 6     impact_flag: 0
blocked: 0

(Event) sensor id: 0    event id: 3     event second:
1319130108 event microsecond: 745191 sig id: 1       gen id: 1 
revision: 1      classification: 0 priority: 0     ip source: 
71.191.147.210       ip destination: 10.181.188.73 src port:
80 dest port: 64916        protocol: 6     impact_flag: 0
blocked: 0 ---END---


-- Eoin





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The demand for IT networking professionals continues to grow, and the
demand for specialized networking skills is growing even more
rapidly. Take a complimentary Learning@Cisco Self-Assessment and
learn about Cisco certifications, training, and career
opportunities. http://p.sf.net/sfu/cisco-dev2dev 
_______________________________________________ Snort-users mailing
list Snort-users () lists sourceforge net Go to this URL to change
user options or unsubscribe: 
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- -- 
- -------------------------------------------------------------------------
John Ives
System & Network Security                           Phone (510) 229-8676
University of California, Berkeley
- -------------------------------------------------------------------------


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