I am not sure if this is the right mailing list for these questions. 

 

What's the best tool to manage modsecurity logs? Keeping in mind that
performance is a concern. 

 

Is there any good article of how to configure  modsecurity for better
performance?

 

Thanks

 

Abdellah

 

 

From: [email protected]
[mailto:[email protected]] On Behalf
Of Mirabito, Massimo (Max) (CDC/OID/OD) (CTR)
Sent: Tuesday, March 08, 2011 1:59 PM
To: '[email protected]'
Cc: Wang, Silver (CDC/OID/OD) (CTR)
Subject: [Owasp-modsecurity-core-rule-set] Rule Set is being violated on
modsecurity_crs_41_phpids_converter.conf line 70

 

Dear All

 

We are having difficulty with one of our applications as it appears that
mod_security is blocking some of the content thinking that it is a
vulnerability.

We are running Apache version 2.2 with mod_security version 2.05

 

 

The url that is giving us problems is as follows:

https://myserver.com/MYAPP/nt/chart/run.do?t=tcg&m=cot/trend&f=png&r=3&y=200
5+to+2009&d=labels_x:[2005,2006,2007,2008,2009,-8.88888888E8,2015];tlabels_x
:[2005,2006,2007,2008,2009];g:[[89.690721649,86.746987952,91.946308725,90,85
.135135135,-8.88888888E8,null],[90,85,87,89,90,-8.88888888E8,null],[83.20913
6562,83.894290701,84.484373669,81.189229619,64.743991641,-8.88888888E8,null]
,[null,null,null,null,null,-8.88888888E8,93]];t:[[194,166,149,150,148],[184,
155,144,141,130],[174,144,137,135,126],[10,11,5,9,18]]&c=0+0+0+0+1&rid=1

 

The peculiar thing is that a similar url runs properly, see below

https:// myserver.com/MYAPP/nt/chart/run.do?
t=pct&m=cot/outcomes&f=png&r=3&y=2009&d=p:[[148,100],[126,85.135135135],[4,2
.7027027027],[0,0],[2,1.3513513514],[1,0.6756756757],[15,10.135135135]]&&rid
=1

 

The logs show the following rule being violated:

Message: Pattern match "(?:[\d+-=\/\* ]+(?:\s?,\s?[\d+-=\/\* ]+)){4,}" at
ARGS:d. [file
"C:/Apache2.2/conf/mod_security/base_rules/modsecurity_crs_41_phpids_convert
er.conf"] [line "70"] [id "973016"] [msg "Basic Charcode Pattern Found"]
[data "2005,2006,2007,2008,2009,-8.88888888e3"]

 

The rule in question is located in modsecurity_crs_41_phpids_converter.conf
- line 70

SecRule ARGS|ARGS_NAMES|XML:/* "(?:[\d+-=\/\* ]+(?:\s?,\s?[\d+-=\/\*
]+)){4,}"
"skip:1,phase:2,capture,t:none,t:urlDecodeUni,t:htmlEntityDecode,t:compressW
hiteSpace,t:lowercase,ctl:auditLogParts=+E,pass,nolog,auditlog,msg:'Basic
Charcode Pattern
Found',id:'973016',tag:'WEB_ATTACK/EVASION',logdata:'%{TX.0}',severity:'4',s
etvar:'tx.msg=%{rule.msg}',setvar:tx.anomaly_score=+%{tx.warning_anomaly_sco
re},setvar:tx.%{rule.id}-WEB_ATTACK/EVASION-%{matched_var_name}=%{tx.0}"

 

My coworker discovered that if we modify a portion of the rule then we are
able to run the application properly. In particular if we modify {4} to {10}
then things begin working

SecRule ARGS|ARGS_NAMES|XML:/* "(?:[\d+-=\/\* ]+(?:\s?,\s?[\d+-=\/\*
]+)){4,}" .. TO ... SecRule ARGS|ARGS_NAMES|XML:/* "(?:[\d+-=\/\*
]+(?:\s?,\s?[\d+-=\/\* ]+)){10,}"

 

We are concerned that by making this change we either inadvertently make our
security weaker or break other things. So we are wondering if the rule has
an inherit problem and is there a way to either resolve it or by pass it or
any other best practice.

 

 

Any feedback is greatly appreciated

 

Thanks,

 

Max 

 

 

 

 

 

 

 

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