Snort mailing list archives

Re: alert 1394 shellcode x86 inc ecx noop


From: Matt Olney <molney () sourcefire com>
Date: Sun, 13 Mar 2011 18:06:02 -0400

Actually, looking at this rule (I was going to bug it), the ports
solution won't work:

alert ip $EXTERNAL_NET any -> $HOME_NET any (msg:"SHELLCODE x86 inc
ecx NOOP"; content:"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
classtype:shellcode-detect; sid:1394; rev:12;)

Because its an IP rule, it ignores port vars.  Um....if you're going
to do what Nigel suggest, covert it to a TCP rule and then use the
SHELLCODE ports.  I think we'll probably look at providing both an IP
and a TCP rule.  If I were forced to make a decision, I'd take the
relatively low risk of missing a shellcode on non-TCP traffic and
avoiding the high-degree of FP that these can cause on web traffic.
But we'll probably provide both and default disable the ip one.  It
will go in the research cue for evaluation.

Bugged for review: 85925

Matt

On Sat, Mar 12, 2011 at 10:06 AM, Nigel Houghton
<nhoughton () sourcefire com> wrote:
On Fri, 11 Mar 2011 22:23:12 -0600, Michael Lubinski wrote:
This seems like one of those rules that you have to significantly
tune in order to get some usefulness out of it. This is a few
payloads its triggering on. My guess is that I just have to start
filtering via threshold.conf.

000 : 75 6D 2E 63 6F 6D 2F 63 6C 6B 3F 32 2C 31 33 3B   um.com/clk?2,13;
010 : 38 62 32 32 31 66 61 61 63 66 35 33 61 36 62 30   8b221faacf53a6b0
020 : 3B 31 32 65 61 37 33 30 61 33 61 36 2C 30 3B 3B   ;12ea730a3a6,0;;
030 : 3B 32 33 32 32 36 33 36 31 39 39 2C 70 77 39 63   ;2322636199,pw9c
040 : 41 4D 4B 63 46 77 43 6F 35 59 41 41 41 41 41 41   AMKcFwCo5YAAAAAA
050 : 41 4B 32 68 49 41 41 41 41 41 41 41 41 41 42 73   AK2hIAAAAAAAAABs
060 : 41 41 59 41 41 41 41 41 41 41 55 41 41 51 41 47   AAYAAAAAAAUAAQAG
070 : 45 68 2D 76 4A 41 41 41 41 41 41 41 54 50 49 71   Eh-vJAAAAAAATPIq
080 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
090 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
0a0 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
0b0 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
0c0 : 41 41 41 41 41 41 41 7A 5A 41 38 41 41 41 41 41   AAAAAAAzZA8AAAAA
0d0 : 41 41 49 41 41 67 41 41 41 41 41 41 70 71 4D 77   AAIAAgAAAAAApqMw
0e0 : 70 79 34 42 41 41 41 41 41 41 41 41 41 47 56 6D   py4BAAAAAAAAAGVm
0f0 : 4D 54 52 6C 4E 7A 63 77 4C 54 52 6A 4D 7A 51 74   MTRlNzcwLTRjMzQt
100 : 4D 54 46 6C 4D 43 31 68 4E 7A 59 78 4C 54 41 77   MTFlMC1hNzYxLTAw
110 : 4D 7A 41 30 4F 47 51 33 4D 57 55 77 4D 41 41 34   MzA0OGQ3MWUwMAA4
120 : 6E 79 6F 41 41 41 41 3D 2C 2C 68 74 74 70 3A 2F   nyoAAAA=,,http:/
130 : 2F 69 6E 74 65 72 61 63 74 69 76 65 73 2E 66 6F   /interactives.fo
140 : 78 31 31 6F 6E 6C 69 6E 65 2E 63 6F 6D 2F 70 68   x11online.com/ph
150 : 6F 74 6F 6D 6F 6A 6F 2F 67 61 6C 6C 65 72 79 2F   otomojo/gallery/
160 : 31 32 35 2F 35 32 2F 6A 61 70 61 6E 2D 71 75 61   125/52/japan-qua
170 : 6B 65 2D 73 70 61 77 6E 73 2D 74 73 75 6E 61 6D   ke-spawns-tsunam
180 : 69 2F 73 75 72 66 65 72 2F 2C 68 74 74 70 3A 2F   i/surfer/,http:/
190 : 2F 61 6C 74 66 61 72 6D 2E 6D 65 64 69 61 70 6C   /altfarm.mediapl
1a0 : 65 78 2E 63 6F 6D 2F 61 64 2F 63 6B 2F 31 32 33   ex.com/ad/ck/123
1b0 : 30 39 2D 31 32 32 35 31 35 2D 31 38 34 33 2D 38   09-122515-1843-8
1c0 : 3F 6D 70 74 3D 31 32 39 39 38 38 35 31 30 36 5C   ?mpt=1299885106\
1d0 : 22 20 74 61 72 67 65 74 3D 5C 22 5F 62 6C 61 6E   " target=\"_blan
1e0 : 6B 5C 22 3E 3C 69 6D 67 20 73 72 63 3D 5C 22 68   k\"><img src=\"h
1f0 : 74 74 70 3A 2F 2F 69 6D 67 2D 63 64 6E 2E 6D 65   ttp://img-cdn.me
200 : 64 69 61 70 6C 65 78 2E 63 6F 6D 2F 30 2F 31 32   diaplex.com/0/12
210 : 33 30 39 2F 31 32 32 35 31 35 2F 31 33 34 32 30   309/122515/13420
220 : 36 35 5F 43 4F 4E 5F 31 32 30 31 30 32 5F 53 59   65_CON_120102_SY
230 : 53 5F 41 43 43 5F 53 54 52 45 41 4B 5F 37 5F 42   S_ACC_STREAK_7_B
240 : 41 5F 54 4D 4F 42 49 4C 45 5F 37 32 38 78 39 30   A_TMOBILE_728x90
250 : 5F 50 52 49 43 45 2E 6A 70 67 5C 22 20 77 69 64   _PRICE.jpg\" wid
260 : 74 68 3D 5C 22 37 32 38 5C 22 20 68 65 69 67 68   th=\"728\" heigh
270 : 74 3D 5C 22 39 30 5C 22 20 62 6F 72 64 65 72 3D   t=\"90\" border=
280 : 5C 22 30 5C 22 20 61 6C 74 3D 5C 22 5C 22 3E 3C   \"0\" alt=\"\"><
290 : 2F 61 3E 22 29 3B 0D 0A 7D 0D 0A 7D 0D 0A 4D 65   /a>");..}..}..Me
2a0 : 64 69 61 70 6C 65 78 46 6C 61 73 68 41 4F 4C 28   diaplexFlashAOL(
2b0 : 29 3B 0D 0A 2F 2F 2D 2D 3E 0D 0A 3C 2F 73 63 72   );..//-->..</scr
2c0 : 69 70 74 3E 0D 0A 3C 2F 62 6F 64 79 3E 0D 0A 3C   ipt>..</body>..<
2d0 : 2F 48 54 4D 4C 3E                                 /HTML>
and another
000 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
010 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
020 : 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41   AAAAAAAAAAAAAAAA
030 : 41 7A 5A 41 38 41 41 41 41 41 41 41 49 41 41 67   AzZA8AAAAAAAIAAg
040 : 41 41 41 41 41 41 33 72 59 74 70 79 34 42 41 41   AAAAAA3rYtpy4BAA
050 : 41 41 41 41 41 41 41 44 64 6A 59 7A 6B 7A 4F 47   AAAAAAADdjYzkzOG
060 : 55 79 4C 54 52 6A 4D 7A 51 74 4D 54 46 6C 4D 43   UyLTRjMzQtMTFlMC
070 : 31 69 59 54 49 30 4C 54 41 77 4D 7A 41 30 4F 47   1iYTI0LTAwMzA0OG
080 : 51 33 4D 7A 45 34 4E 41 41 34 6E 79 6F 41 41 41   Q3MzE4NAA4nyoAAA
090 : 41 3D 2C 2C 68 74 74 70 25 33 41 25 32 46 25 32   A=,,http%3A%2F%2
0a0 : 46 69 6E 74 65 72 61 63 74 69 76 65 73 2E 66 6F   Finteractives.fo
0b0 : 78 31 31 6F 6E 6C 69 6E 65 2E 63 6F 6D 25 32 46   x11online.com%2F
0c0 : 70 68 6F 74 6F 6D 6F 6A 6F 25 32 46 67 61 6C 6C   photomojo%2Fgall
0d0 : 65 72 79 25 32 46 31 32 35 25 32 46 36 25 32 46   ery%2F125%2F6%2F
0e0 : 6A 61 70 61 6E 2D 71 75 61 6B 65 2D 73 70 61 77   japan-quake-spaw
0f0 : 6E 73 2D 74 73 75 6E 61 6D 69 25 32 46 63 61 72   ns-tsunami%2Fcar
100 : 73 2D 77 61 73 68 65 64 2D 61 77 61 79 25 32 46   s-washed-away%2F
110 : 2C 68 74 74 70 3A 2F 2F 77 77 77 2E 73 6D 61 72   ,http://www.smar
120 : 74 65 72 6C 69 66 65 73 74 79 6C 65 73 2E 63 6F   terlifestyles.co
130 : 6D 2F 32 30 31 31 2F 30 31 2F 32 35 2F 6F 6E 65   m/2011/01/25/one
140 : 2D 73 6B 69 6E 63 61 72 65 2D 62 72 61 6E 64 2D   -skincare-brand-
150 : 64 65 6C 69 76 65 72 73 2D 77 6F 6D 65 6E 2D 6D   delivers-women-m
160 : 6F 72 65 2D 79 6F 75 74 68 66 75 6C 2D 73 6B 69   ore-youthful-ski
170 : 6E 25 45 32 25 38 30 25 39 34 61 74 2D 65 76 65   n%E2%80%94at-eve
180 : 72 79 2D 61 67 65 2F 3F 66 63 5F 69 64 3D 32 33   ry-age/?fc_id=23
190 : 31 35 36 26 66 63 5F 61 70 70 5F 69 64 3D 33 39   156&fc_app_id=39
1a0 : 39 33 22 20 74 61 72 67 65 74 3D 22 5F 62 6C 61   93" target="_bla
1b0 : 6E 6B 22 3E 0A 20 20 20 20 20 20 20 20 20 20 20   nk">.
1c0 : 20 20 20 20 20 41 20 73 68 6F 63 6B 69 6E 67 20        A shocking
1d0 : 73 6B 69 6E 20 74 72 69 63 6B 20 68 61 73 20 77   skin trick has w
1e0 : 6F 6D 65 6E 20 65 76 65 72 79 77 68 65 72 65 20   omen everywhere
1f0 : 74 61 6C 6B 69 6E 67 2E 20 5B 53 74 61 67 65 73   talking. [Stages
200 : 20 6F 66 20 42 65 61 75 74 79 5D 3C 2F 61 3E 0A    of Beauty]</a>.
210 : 20 20 20 20 20 20 20 20 3C 2F 64 69 76 3E 0A 20           </div>.
220 : 20 20 20 20 20 3C 2F 74 64 3E 0A 20 20 20 20 3C        </td>.    <
230 : 2F 74 72 3E 0A 20 20 20 20 3C 2F 74 62 6F 64 79   /tr>.    </tbody
240 : 3E 0A 3C 2F 74 61 62 6C 65 3E 0A 0A 3C 2F 74 64   >.</table>..</td
250 : 3E 0A 20 20 20 20 20 20 20 20 20 20 20 20 3C 2F   >.            </
260 : 74 72 3E 0A 20 20 20 20 20 20 20 20 3C 74 72 3E   tr>.        <tr>
270 : 0A 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20   .
280 : 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
290 : 20 20 20 20 20 20 20 20 20 20 20 20 20 3C 74 64                <td
2a0 : 3E 0A 20 20 20 20 20 20 20 20 20 20 20 20 20 20   >.
2b0 : 20 20 20 20 20 20 20 20 20 20 20 20 20 20 3C 6C                 <l
2c0 : 69 6E 6B 20 72 65 6C 3D 22 73 74 79 6C 65 73 68   ink rel="stylesh
2d0 : 65 65 74 22 20 68 72 65 66 3D 22 68 74 74 70 3A   eet" href="http:
2e0 : 2F 2F 73 74 61 74 69 63 2E 63 64 6E 2E 61 64 62   //static.cdn.adb
2f0 : 6C 61 64 65 2E 63 6F 6D 2F 63 73 73 2F 61 64 54   lade.com/css/adT
300 : 65 6D 70 6C 61 74 65 73 2F 61 64 54 79 70 65 31   emplates/adType1
310 : 5F 7A 6F 6E 65 38 33 2E 63 73 73 22 20 74 79 70   _zone83.css" typ
320 : 65 3D 22 74 65 78 74 2F 63 73 73 22 20 2F 3E 20   e="text/css" />
330 : 0A 20 20 20 20 20 20 20 20 3C 73 74 79 6C 65 3E   .        <style>
340 : 0A 20 20 20 20 20 20 20 20 20 20 20 20 2E 61 64   .            .ad
350 : 54 69 74 6C 65 31 5F 38 33 2C 20 2E 61 64 54 69   Title1_83, .adTi
360 : 74 6C 65 31 5F 38 33 3A 6C 69 6E 6B 2C 20 2E 61   tle1_83:link, .a
370 : 64 54 69 74 6C 65 31 5F 38 33 3A 76 69 73 69 74   dTitle1_83:visit
380 : 65 64 2C 20 2E 61 64 54 69 74 6C 65 31 5F 38 33   ed, .adTitle1_83
390 : 3A 68 6F 76 65 72 2C 0A 20 20 20 20 20 20 20 20   :hover,.
3a0 : 20 20 20 20 2E 61 64 4C 65 61 72 6E 4D 6F 72 65       .adLearnMore
3b0 : 4C 69 6E 6B 31 5F 38 33 2C 20 2E 61 64 4C 65 61   Link1_83, .adLea
3c0 : 72 6E 4D 6F 72 65 4C 69 6E 6B 31 5F 38 33 3A 6C   rnMoreLink1_83:l
3d0 : 69 6E 6B 2C 20 2E 61 64 4C 65 61 72 6E 4D 6F 72   ink, .adLearnMor
3e0 : 65 4C 69 6E 6B 31 5F 38 33 3A 76 69 73 69 74 65   eLink1_83:visite
3f0 : 64 2C 20 2E 61 64 4C 65 61 72 6E 4D 6F 72 65 4C   d, .adLearnMoreL
400 : 69 6E 6B 31 5F 38 33 3A 68 6F 76 65 72 20 7B 0A   ink1_83:hover {.
410 : 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
420 : 63 6F 6C 6F 72 3A 23 30 30 30 30 30 30 3B 20 20   color:#000000;
430 : 20 20 20 20 20 20 20 20 20 20 20 20 20 20 66 6F                 fo
440 : 6E 74 2D 66 61 6D 69 6C 79 3A 41 72 69 61 6C 2C   nt-family:Arial,
450 : 48 65 6C 76 65 74 69 63 61 2C 73 61 6E 73 2D 73   Helvetica,sans-s
460 : 65 72 69 66 3B 20 20 20 20 20 20 20 20 20 20 20   erif;
470 : 20 7D 0A 20 20 20 20 20 20 20 20 20 20 20 20 2E    }.            .
480 : 61 64 44 65 73 63 72 69 70 74 69 6F 6E 31 5F 38   adDescription1_8
490 : 33 2C 20 2E 61 64 44 65 73 63 72 69 70 74 69 6F   3, .adDescriptio
4a0 : 6E 31 5F 38 33 3A 6C 69 6E 6B 2C 20 2E 61 64 44   n1_83:link, .adD
4b0 : 65 73 63 72 69 70 74 69 6F 6E 31 5F 38 33 3A 76   escription1_83:v
4c0 : 69 73 69 74 65 64 2C 20 2E 61 64 44 65 73 63 72   isited, .adDescr
4d0 : 69 70 74 69 6F 6E 31 5F 38 33 3A 68 6F 76 65 72   iption1_83:hover
4e0 : 20 7B 0A 20 20 20 20 20 20 20 20 20 20 20 20 20    {.
4f0 : 20 20 20 63 6F 6C 6F 72 3A 23 30 30 36 36 63 63      color:#0066cc
500 : 3B 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20   ;
510 : 20 66 6F 6E 74 2D 66 61 6D 69 6C 79 3A 41 72 69    font-family:Ari
520 : 61 6C 2C 48 65 6C 76 65 74 69 63 61 2C 73 61 6E   al,Helvetica,san
530 : 73 2D 73 65 72 69 66 3B 20 20 20 20 20 20 20 20   s-serif;
540 : 20 20 20 20 7D 0A 20 20 20 20 20 20 20 20 20 20       }.
550 : 20 20 2E 61 64 49 6D 61 67 65 31 5F 38 33 20 7B     .adImage1_83 {
560 : 0A 20 20 20                                       .

Am i wrong in assuming that this alert should generate some fp's due
to its nature?

Looks like web traffic. So yes, the outlook is good for false positive
events. In your snort.conf you should see this:

# List of ports you want to look for SHELLCODE on.
portvar SHELLCODE_PORTS !80

If the traffic you are seeing is web traffic on another port, you might
want to change that port to a list.

Now you can use the $SHELLCODE_PORTS variable in the rule instead of
"any". You should be able to configure PulledPork to do this for you
each time you update your rules.

If you do that, then Snort will not evaluate traffic on that port for
the conditions in that rule. If you use event_filter or suppress in
your threshold.conf, it will continue to evaluate the traffic and still
give you events (although not as often depending on the event_filter
and not at all with suppress of course)

--
Nigel Houghton
Head Mentalist
SF VRT Department of Intelligence Excellence
http://vrt-blog.snort.org/ && http://labs.snort.org/

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