[Snort-users] base64 snort options

whliudunjun whliudunjun at ...7427...
Sun Jun 10 23:53:30 EDT 2012


Hi,Joel Esler,
Thanks for your quickly reply,here i will post my pcap :f43b7121dadb17ff057bfdbba9b0c18f.pcap and the snort -T output if that you can know what's my trouble,i still cant use any sig detected the said traffic,when i use:
----------------------------------------------------------------------------------------------------------------------------------------------------------
alert tcp $EXTERNAL_NET $HTTP_PORTS -> $EXTERNAL_NET $HTTP_PORTS (msg:"base64 returned from outbound post"; flow:to_client,established; flowbits:isset,badpost; content:"200"; http_stat_code; content:"text/html"; http_header; base64_decode:relative; base64_data;  content:"webmail.vigilante.dk"; sid:10000043;rev:1;).
----------------------------------------------------------------------------------------------------------------------------------------------------------
snort -A fast -b -d -r f43b7121dadb17ff057bfdbba9b0c18f.pcap  -c /opt/snort/etc/test.conf
 
nothing alert log.
 
Thanks.

At 2012-06-09 03:44:38,"Joel Esler" <jesler at ...1935...> wrote:
>alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Suspicious outbound post"; flow:to_server,established; content:"POST"; http_method; content:"index.php"; http_uri; flowbits:set,badpost; flowbits:noalert; sid:1;)
>
>alert tcp $EXTERNAL_NET $HTTP_PORTS -> $EXTERNAL_NET $HTTP_PORTS (msg:"base64 returned from outbound post"; flow:to_client,established; flowbits:isset,badpost; content:"200"; http_stat_code; content:"text/html"; base64_decode:relative; base64_data;  content:"webmail.vigilante.dk"; sid:2;)
>
>or
>
>alert tcp $EXTERNAL_NET $HTTP_PORTS -> $EXTERNAL_NET $HTTP_PORTS (msg:"base64 returned from outbound post"; flow:to_client,established; flowbits:isset,badpost; content:"200"; http_stat_code; content:"text/html"; base64_decode:relative; base64_data;  content:"varchar("; content:"cast("; distance:0; sid:3;)
>
>Actually the below won't work, the above should.
>
>
>On Jun 8, 2012, at 3:43 PM, Joel Esler wrote:
>
>> Maybe something like this:
>> 
>> alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Suspicious outbound post"; flow:to_server,established; content:"POST"; http_method; content:"index.php"; http_uri; flowbits:set,badpost; flowbits:noalert; sid:1;)
>> 
>> alert tcp $EXTERNAL_NET $HTTP_PORTS -> $EXTERNAL_NET $HTTP_PORTS (msg:"base64 returned from outbound post"; flow:to_client,established; flowbits:isset,badpost; content:"200"; http_stat_code; content:"text/html"; http_header; base64_decode:relative; base64_data;  content:"webmail.vigilante.dk"; sid:2;)
>> 
>> or
>> 
>> alert tcp $EXTERNAL_NET $HTTP_PORTS -> $EXTERNAL_NET $HTTP_PORTS (msg:"base64 returned from outbound post"; flow:to_client,established; flowbits:isset,badpost; content:"200"; http_stat_code; content:"text/html"; http_header; base64_decode:relative; base64_data;  content:"varchar("; content:"cast("; distance:0; sid:3;)
>> 
>> 
>> 
>> 
>> Note, I wrote those off the top of my head.  I didn't test them as I don't have a pcap of the traffic.
>> 
>> --
>> Joel Esler
>> Senior Research Engineer, VRT
>> OpenSource Community Manager
>> Sourcefire
>> 
>> 
>> On Jun 8, 2012, at 2:05 AM, whliudunjun wrote:
>> 
>>> when i use snort to scan pcap package,the net traffic like following:
>>> 
>>> the traffic:---------------------------------------------------------------------------------------
>>> send:
>>> POST /metcon/index.php?id=73EEFFDBC2080030429BE52FA2866576 HTTP/1.1
>>> Content-Type: application/x-www-form-urlencoded
>>> User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Axo 9.104.044 )
>>> Host: 178.157.202.31
>>> Content-Length: 4
>>> Cache-Control: no-cache
>>> INIT
>>> receive:
>>> HTTP/1.1 200 OK
>>> Date: Wed, 06 Jun 2012 09:58:00 GMT
>>> Server: Apache
>>> Vary: Accept-Encoding
>>> Content-Length: 2196
>>> Content-Type: text/html
>>> d2VibWFpbC52aWdpbGFudGUuZGs=#ODA=#MDAwMA==#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#X19fXw==#TW96aWxsYS81LjAgKFdpbmRvd3MgTlQgNS4xKSBBcHBsZVdlYktpdC81MzUuMTkgKEtIVE1MLCBsaWtlIEdlY2tvKSBDaHJvbWUvMTguMC4xMDI1LjE2MiBTYWZhcmkvNTM1LjE5##fDgxMw==#
>>> 
>>> end-------------------------------------------------------------------------------------------------------------------------------------------------------
>>> 
>>> base64:
>>> d2VibWFpbC52aWdpbGFudGUuZGs=#
>>> ascii:webmail.vigilante.dk
>>> 
>>> the receive data is encode using base64,so i write a snort rules to detected it:
>>> 41 alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"Trojan SQL injection code receive"; flow:to_client,established;content:"HTTP/1.1 200 OK";content:"webmail.vigilante.dk";clas    stype:trojan-activity; sid:10000043; rev:1;)
>>> 
>>> why this sig can't detect above traffic,is there anyone can tell me why?or i write rules at a wrong way,or i need to open some config option.
>>> 
>>> 
>>> 
>>> 
>>> 
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>> 
>
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