[Snort-users] base64 snort options

Joel Esler jesler at ...1935...
Mon Jun 11 08:32:00 EDT 2012


<have not looked at pcap>

You have to use both sigs I gave you below.


On Jun 10, 2012, at 11:53 PM, whliudunjun wrote:

> 
> 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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> >
> 
> 
> 
> <pcap.zip>





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