Re: http_inspect tuning issue

["Castle, Shane" <scastle () bouldercounty org>]

I want to tune then out because they seem to be completely useless. No info other than the bald message is ever given, 
no packet in which the offense occurred is captured by Snort as part of the process, and if the NSM logs are searched 
for the corresponding event then you see something like this:
------------------------------------------------------------------------
POST /dgw?imei=TEST&apptype=finance&src=HTC01 HTTP/1.1
User-Agent: curl/7.19.0 (i586-pc-mingw32msvc) libcurl/7.19.0 zlib/1.2.3
Content-Type: text/xml
Content-Length: 335
Host: api.htc.go.yahoo.com
Connection: Keep-Alive

<?xml version="1.0" encoding="UTF-8"?>
<request devtype="HTC_Model" deployver="HTCFinanceWidget 0.1" app="HTCFinanceWidget" appver="0.1.0" api="finance" 
apiver="1.0.1" acknotification="0000">
<query id="0" timestamp="0" type="getquotes">
<list><symbol>^DJI</symbol><symbol>^GSPC</symbol><symbol>^IXIC</symbol></list></query>
</request>

HTTP/1.1 200 OK
Date: Mon, 02 Jul 2012 22:18:56 GMT
X-YSTATUS: 200
Vary: Accept-Encoding
Connection: close
Transfer-Encoding: chunked
Content-Type: text/plain;charset=UTF-8
Cache-Control: private

576    
<?xml version="1.0" encoding="UTF-8"?><response><result type="getquotes" timestamp="1341267536"><list count="3" 
total="3"><quote><name>Dow Jones Industrial 
Average</name><symbol>^DJI</symbol><exchange>DJI</exchange><status>0</status><timestamp>1341259357</timestamp><price>12871.389648</price><change>-8.700195</change><changepercent>-0.067548</changepercent><open>12879.709961</open><high>12902.120117</high><low>12795.480469</low><volume>109643561</volume><marketcap>N/A</marketcap><link>http://m.yahoo.com/s/htcwf/yfinance/quote/^DJI/</link></quote><quote><name>S&amp;P
 
500</name><symbol>^GSPC</symbol><exchange>SNP</exchange><status>0</status><timestamp>1341261519</timestamp><price>1365.510010</price><change>3.349976</change><changepercent>0.245931</changepercent><open>1362.329956</open><high>1366.349976</high><low>1355.699951</low><volume>544915121</volume><marketcap>N/A</marketcap><link>http://m.yahoo.com/s/htcwf/yfinance/quote/^GSPC/</link></quote><quote><name>NASDAQ
 
Composite</name><symbol>^IXIC</symbol><exchange>Nasdaq</exchange><status>0</status><timestamp>1341263923</timestamp><price>2951.229980</price><change>16.180000</change><changepercent>0.551268</changepercent><open>2938.409912</open><high>2951.229980</high><low>2925.709961</low><volume>0</volume><marketcap>N/A</marketcap><link>http://m.yahoo.com/s/htcwf/yfinance/quote/^IXIC/</link></quote></list></result></response>

0
------------------------------------------------------------------------
Here's another one:
------------------------------------------------------------------------
GET / HTTP/1.1
Accept: */*
Accept-Language: en-us
UA-CPU: x86
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB7.3; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 
3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)
Host: my-cdhs.state.co.us
Connection: Keep-Alive
Cookie: GUEST_LANGUAGE_ID=en_US; COOKIE_SUPPORT=true; LOGIN="cn=greenxrj,ou=hsp,ou=bda,ou=nc,o=cty"

HTTP/1.1 302 Moved Temporarily
Location: https://my-cdhs.state.co.us/
Connection: close
Cache-Control: no-cache
Pragma: no-cache
------------------------------------------------------------------------
Now, what's the point of this alert? Even if there is actually an error in the HTTP conversation (which there does seem 
to be, but I can't see the issue in the second example) there is nothing harmful or malicious here. One thing I do 
notice: many of the servers belong to Yahoo. If I could tune out just those I think I could reduce my noise. But I 
still think that fundamentally 120:8 is useless and I'm going to try thresholding it so I don't see it anymore.

-- 
Shane Castle
Data Security Mgr, Boulder County IT
CISSP GSEC GCIH

-----Original Message-----
From: waldo kitty [mailto:wkitty42 () windstream net] 
Sent: Monday, July 02, 2012 23:31
To: snort-users () lists sourceforge net
Subject: Re: [Snort-users] http_inspect tuning issue

On 7/2/2012 18:53, Castle, Shane wrote:
> I am getting thousands of 120:8 alerts (http_inspect: MESSAGE WITH INVALID CONTENT-LENGTH OR CHUNK SIZE) and I can't 
> figure out how to tune http_inspect so that they aren't triggered. Any info on this would be appreciated.

why would you want to tune them out? what do your pcaps (packet captures) show? 
this, to me, stinks of some sort of consolidated attack on your servers or 
possibly of trying to use them in an attack against another server or servers...

i say this while looking at the thousands of attacks that my systems repel every 
day which are trying to use my servers against other servers... the main key 
factor in my case is that they are caught and automatically blocked before they 
can infiltrate my servers... yes, this is "slightly" against the normal flow 
processing of monitoring IDS/IPS alerts but it is the process that i and those i 
support have chosen ;)

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