[Bro] Assertion failure, Tag.cc

Michael Fry michael.fry at morphick.com
Mon Jul 25 08:10:23 PDT 2016


Apologies for the delay. Below is the minimal script that will reproduce
the core dump. As described earlier, files.log shows the same FUID with
different connections multiple times. This causes the
file_extraction_limit() to be called multiple times for the same file.
Removing my event handler side-steps the core dump.

redef FileExtract::prefix = "/tmp/bro";


# Files of sizes outside this range will be discarded

global min_file_size: count = 1024;

global max_file_size: count = 5000000;



event bro_init()

{

        mkdir(FileExtract::prefix);

}


event file_sniff(f: fa_file, meta: fa_metadata)

{

        if (f$source != "HTTP")

                return;


        Files::add_analyzer(f, Files::ANALYZER_EXTRACT,
[$extract_limit=max_file_size]);

        Files::add_analyzer(f, Files::ANALYZER_MD5);

}


event file_state_remove(f: fa_file)

{

        if (f$info?$extracted)

        {

                print(fmt("Deleting %s, size=%s", f$info$extracted,
f$seen_bytes));

                system(fmt("rm \"/tmp/bro/%s\"",
str_shell_escape(f$info$extracted)));

        }

}


event file_extraction_limit(f: fa_file , args: any , limit: count , len:
count)

{

        print "file_extraction_limit():", f;

        flush_all();

}

Here is an example that led to a crash. Note the same FUID is logged
multiple times with different connection UIDs.

root at redacted:/opt/cbts/log/bro/2016-06-28# zgrep FBzliCXoEipv0oEM8 *
files.2016-06-28-18-00-00.log.dz:1467138209.682287      FBzliCXoEipv0oEM8
    13.107.4.50     10.100.162.133  CapHn31QDgLbeGCqIh      HTTP    0
EXTRACT,SHA1,MD5        application/zip
Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle
 0.010122        F       F       22610   8811168 0       0       F       -
      02af20e0f97904b4c9da2c5a0071c324
 b09760ed7e7f64e389eb709abf97cbbc395cd22a        -
HTTP-FBzliCXoEipv0oEM8-Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle.file
files.2016-06-28-18-00-00.log.dz:1467138211.315952      FBzliCXoEipv0oEM8
    13.107.4.50     10.100.162.133  CbGwtH2ajMS3nq8oR9      HTTP    0
MD5,SHA1,EXTRACT        application/zip
Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle
 0.007328        F       F       13850   8811168 0       0       F       -
      7d8f20dc6941d42cb735bfbb1f5dee1d
 dccb1e3e513ab377ee909823c538ba196140a6df        -
HTTP-FBzliCXoEipv0oEM8-Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle.file
files.2016-06-28-18-00-00.log.dz:1467138211.234745      FBzliCXoEipv0oEM8
    13.107.4.50     10.100.162.133  ClZAlx4VvTPCGXWnGf      HTTP    0
SHA1,EXTRACT,MD5        application/zip
Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle
 0.010127        F       F       22610   8811168 0       0       F       -
      02af20e0f97904b4c9da2c5a0071c324
 b09760ed7e7f64e389eb709abf97cbbc395cd22a        -
HTTP-FBzliCXoEipv0oEM8-Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle.file
files.2016-06-28-18-00-00.log.dz:1467138211.395275      FBzliCXoEipv0oEM8
    13.107.4.50     10.100.162.133  C1PiIFx6hRC32DES9       HTTP    0
SHA1,MD5,EXTRACT        application/zip
Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle
 0.008257        F       F       16770   8811168 0       0       F       -
      c6c39cc6b8a6773a8b4b416a919cfca6
 0ae53083b1fc02d7710e9c2b12ad930990e73c8e        -
HTTP-FBzliCXoEipv0oEM8-Microsoft.Getstarted_3.11.1.0_neutral_~_8wekyb3d8bbwe.AppxBundle.file
http.2016-06-28-18-00-00.log.dz:1467138209.662449       CapHn31QDgLbeGCqIh
     10.100.162.133  61074   13.107.4.50     80      2       GET
tlu.dl.delivery.mp.microsoft.com
 /filestreamingservice/files/9f5dbc38-f074-45be-8346-ca45b940a576?P1=1467138990&P2=301&P3=2&P4=M61a7Qj+Xwl55JKMXfAzkJPsnDstij/KQXct1zwrcGI=
     -       Microsoft BITS/7.8      0       22610   200     OK      -
  --      (empty) -       -       -       -       -       FBzliCXoEipv0oEM8
      application/zip
http.2016-06-28-18-00-00.log.dz:1467138209.748598       CalgEr4pL03r1nZKql
     10.100.162.133  61075   13.107.4.50     80      1       GET
tlu.dl.delivery.mp.microsoft.com
 /filestreamingservice/files/9f5dbc38-f074-45be-8346-ca45b940a576?P1=1467138990&P2=301&P3=2&P4=M61a7Qj+Xwl55JKMXfAzkJPsnDstij/KQXct1zwrcGI=
     -       Microsoft BITS/7.8      0       94880   206     Partial
Content -       -       -       (empty) -       -       -       -       -
    FBzliCXoEipv0oEM8       -
http.2016-06-28-18-00-00.log.dz:1467138211.295292       CbGwtH2ajMS3nq8oR9
     10.100.162.133  61077   13.107.4.50     80      1       GET
tlu.dl.delivery.mp.microsoft.com
 /filestreamingservice/files/9f5dbc38-f074-45be-8346-ca45b940a576?P1=1467138990&P2=301&P3=2&P4=M61a7Qj+Xwl55JKMXfAzkJPsnDstij/KQXct1zwrcGI=
     -       Microsoft BITS/7.8      0       13850   200     OK      -
  --      (empty) -       -       -       -       -       FBzliCXoEipv0oEM8
      application/zip
http.2016-06-28-18-00-00.log.dz:1467138211.214133       ClZAlx4VvTPCGXWnGf
     10.100.162.133  61076   13.107.4.50     80      1       GET
tlu.dl.delivery.mp.microsoft.com
 /filestreamingservice/files/9f5dbc38-f074-45be-8346-ca45b940a576?P1=1467138990&P2=301&P3=2&P4=M61a7Qj+Xwl55JKMXfAzkJPsnDstij/KQXct1zwrcGI=
     -       Microsoft BITS/7.8      0       22610   200     OK      -
  --      (empty) -       -       -       -       -       FBzliCXoEipv0oEM8
      application/zip
http.2016-06-28-18-00-00.log.dz:1467138211.373513       C1PiIFx6hRC32DES9
    10.100.162.133  61078   13.107.4.50     80      1       GET
tlu.dl.delivery.mp.microsoft.com
 /filestreamingservice/files/9f5dbc38-f074-45be-8346-ca45b940a576?P1=1467138990&P2=301&P3=2&P4=M61a7Qj+Xwl55JKMXfAzkJPsnDstij/KQXct1zwrcGI=
     -       Microsoft BITS/7.8      0       16770   200     OK      -
  --      (empty) -       -       -       -       -       FBzliCXoEipv0oEM8
      application/zip

Thanks,
Mike

On Thu, Jun 30, 2016 at 12:02 AM Seth Hall <seth at icir.org> wrote:

>
> > On Jun 29, 2016, at 6:58 PM, Michael Fry <michael.fry at morphick.com>
> wrote:
> >
> > I've been able to narrow down the circumstances where we see this core
> dump. In the dozens of times that I've seen it, the file being extracted is
> always delivered over HTTP via the BITS client.
>
> Could you send the script that you are using which causes this problem?
>
>   .Seth
>
> --
> Seth Hall
> International Computer Science Institute
> (Bro) because everyone has a network
> http://www.bro.org/
>
>
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