ModSecurity 2.7.5 for Nginx 1.4.2 duplicate charset headers #568
Comments
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Original reporter: wellumies |
ghost
assigned
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wellumies: In addition to the header problem no files over 8k are passed to the backend :( input filter's nbytes=-1 is interesting [30/Aug/2013:09:33:38 +0300] [/sid#7f1f5fa160a0][rid#7f1f5f9af0a0][/cart/][4] Initialising transaction (txid Ac7cAcAKAcAcZHAcAcAwAcAc). |
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wellumies: Is there any comment on this? Our client is waiting with their Nginx LBs ready and only thing missing is a working ModSec |
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wellumies: There really should be way to toggle if you don't want ModSec to add the charset-header or not BUG: Garbage at the end of content_type header. REASON: Ngx_snprintf does not terminate the string. Neither does PROPOSED FIX: diff --git a/nginx/modsecurity/ngx_http_modsecurity.c
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wellumies: Files over 8k are not send to backend. BUG: Requests in excess of 8k are not forwarded. REASON: It seems only the first chunk is forwarded--there's no logic to PROPOSED FIX: +again:
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zimmerle: Hi Veli, Just placed a pull request to fix the bug that you have reported, the pull request is available at: Thanks, |
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rbarnett: This will be part of our next release - v2.7.6. |
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Hi there, Is there a way to prevent MODSEC from adding the charset-header at all (assuming this is expected behaviour)? If we can actually do that ... are we going to break some modsec functionality ? At the moment I have an issue where with modsecurity enabled we appear to be seeing duplicate charset attributes... for example, Content-Type: text/xml; Charset=UTF-8; charset=UTF-8;.... browsers will ignore the duplicate "Charset=UTF-8; charset=UTF-8"; but this is breaking one of my applications (we think that possibly MSXML is choking on it (when it retrieves such content using a document() call)).. just doesn't like that double charset.... the page throws the following error: "....System does not support the specified encoding......" MORE INFO: Thanks. Leonel |
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Hi @leonelr, There was an update on the way that we have set this header. It is fixed under our development tree. Br., |
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THE update using the branch "Master" did not work. Perhaps you can send me the actual link for the download? |
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Sorry to be a pain, but I really need to sort this one out .... can anyone give me an update / confirm that this has been resolved ? L.R. |
MODSEC-420: When I disable ModSecurity from nginx.conf my backend provides charset header correctly
sec-176:~ wellu$ curl --head http://111.111.111.111/interface/ShopName?ffg
HTTP/1.1 200 OK
Server: nginx/1.4.2
Date: Thu, 29 Aug 2013 14:34:18 GMT
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
Set-Cookie: MCFS=b4v6gu0c0fsmdtj52rla35eg06; expires=Mon, 28-May-2057 05:09:58 GMT; path=/; domain=.111.111; HttpOnly
Cache-Control: no-cache
Pragma: no-cache
Expires: -1
X-Content-Type-Options: nosniff
XSS-Protection: 1; mode=block
X-Varnish: 579266232
When I enable ModSecurity for this server and just use the basic modsecurity.conf I get duplicate charset headers and also the X-headers are removed. Also the char after UTF-8 depends on how many chars after '?' I use in the URL
sec-176:~ wellu$ curl --head http://111.111.111.111/interface/ShopName?ffg
HTTP/1.1 200 OK
Server: nginx/1.4.2
Date: Thu, 29 Aug 2013 14:35:18 GMT
Content-Type: text/html; charset=UTF-8; charset=UTF-8?
Connection: keep-alive
Set-Cookie: MCFS=rknbdjna7m1oi5qh9pk6uqmrm7; expires=Mon, 28-May-2057 05:12:00 GMT; path=/; domain=.111.111; HttpOnly
Cache-Control: no-cache
Expires: -1
modsecurity.conf
-- Rule engine initialization ----------------------------------------------
Enable ModSecurity, attaching it to every transaction. Use detection
only to start with, because that minimises the chances of post-installation
disruption.
SecRuleEngine DetectionOnly
-- Request body handling ---------------------------------------------------
Allow ModSecurity to access request bodies. If you don't, ModSecurity
won't be able to see any POST parameters, which opens a large security
hole for attackers to exploit.
SecRequestBodyAccess On
Enable XML request body parser.
Initiate XML Processor in case of xml content-type
SecRule REQUEST_HEADERS:Content-Type "text/xml"
"id:'200000',phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=XML"
Maximum request body size we will accept for buffering. If you support
file uploads then the value given on the first line has to be as large
as the largest file you are willing to accept. The second value refers
to the size of data, with files excluded. You want to keep that value as
low as practical.
SecRequestBodyLimit 13107200
SecRequestBodyLimit 22020096
SecRequestBodyNoFilesLimit 131072
Store up to 128 KB of request body data in memory. When the multipart
parser reachers this limit, it will start using your hard disk for
storage. That is slow, but unavoidable.
SecRequestBodyInMemoryLimit 131072
What do do if the request body size is above our configured limit.
Keep in mind that this setting will automatically be set to ProcessPartial
when SecRuleEngine is set to DetectionOnly mode in order to minimize
disruptions when initially deploying ModSecurity.
SecRequestBodyLimitAction Reject
Verify that we've correctly processed the request body.
As a rule of thumb, when failing to process a request body
you should reject the request (when deployed in blocking mode)
or log a high-severity alert (when deployed in detection-only mode).
SecRule REQBODY_ERROR "!@eq 0"
"id:'200001', phase:2,t:none,log,deny,status:400,msg:'Failed to parse request body.',logdata:'%{reqbody_error_msg}',severity:2"
By default be strict with what we accept in the multipart/form-data
request body. If the rule below proves to be too strict for your
environment consider changing it to detection-only. You are encouraged
not to remove it altogether.
SecRule MULTIPART_STRICT_ERROR "!@eq 0"
"id:'200002',phase:2,t:none,log,deny,status:44,
msg:'Multipart request body failed strict validation:
PE %{REQBODY_PROCESSOR_ERROR},
BQ %{MULTIPART_BOUNDARY_QUOTED},
BW %{MULTIPART_BOUNDARY_WHITESPACE},
DB %{MULTIPART_DATA_BEFORE},
DA %{MULTIPART_DATA_AFTER},
HF %{MULTIPART_HEADER_FOLDING},
LF %{MULTIPART_LF_LINE},
SM %{MULTIPART_MISSING_SEMICOLON},
IQ %{MULTIPART_INVALID_QUOTING},
IP %{MULTIPART_INVALID_PART},
IH %{MULTIPART_INVALID_HEADER_FOLDING},
FL %{MULTIPART_FILE_LIMIT_EXCEEDED}'"
Did we see anything that might be a boundary?
SecRule MULTIPART_UNMATCHED_BOUNDARY "!@eq 0"
"id:'200003',phase:2,t:none,log,deny,msg:'Multipart parser detected a possible unmatched boundary.'"
PCRE Tuning
We want to avoid a potential RegEx DoS condition
SecPcreMatchLimit 1000
SecPcreMatchLimitRecursion 1000
Some internal errors will set flags in TX and we will need to look for these.
All of these are prefixed with "MSC_". The following flags currently exist:
MSC_PCRE_LIMITS_EXCEEDED: PCRE match limits were exceeded.
SecRule TX:/^MSC_/ "!@Streq 0"
"id:'200004',phase:2,t:none,deny,msg:'ModSecurity internal error flagged: %{MATCHED_VAR_NAME}'"
-- Response body handling --------------------------------------------------
Allow ModSecurity to access response bodies.
You should have this directive enabled in order to identify errors
and data leakage issues.
Do keep in mind that enabling this directive does increases both
memory consumption and response latency.
SecResponseBodyAccess Off
Which response MIME types do you want to inspect? You should adjust the
configuration below to catch documents but avoid static files
(e.g., images and archives).
SecResponseBodyMimeType text/plain text/html text/xml
Buffer response bodies of up to 512 KB in length.
SecResponseBodyLimit 524288
What happens when we encounter a response body larger than the configured
limit? By default, we process what we have and let the rest through.
That's somewhat less secure, but does not break any legitimate pages.
SecResponseBodyLimitAction ProcessPartial
-- Filesystem configuration ------------------------------------------------
The location where ModSecurity stores temporary files (for example, when
it needs to handle a file upload that is larger than the configured limit).
This default setting is chosen due to all systems have /tmp available however,
this is less than ideal. It is recommended that you specify a location that's private.
SecTmpDir /var/log/modsecurity_workdir/
The location where ModSecurity will keep its persistent data. This default setting
is chosen due to all systems have /tmp available however, it
too should be updated to a place that other users can't access.
SecDataDir /var/log/modsecurity_workdir/
-- File uploads handling configuration -------------------------------------
The location where ModSecurity stores intercepted uploaded files. This
location must be private to ModSecurity. You don't want other users on
the server to access the files, do you?
SecUploadDir /var/log/modsecurity_workdir/
By default, only keep the files that were determined to be unusual
in some way (by an external inspection script). For this to work you
will also need at least one file inspection rule.
SecUploadKeepFiles RelevantOnly
Uploaded files are by default created with permissions that do not allow
any other user to access them. You may need to relax that if you want to
interface ModSecurity to an external program (e.g., an anti-virus).
SecUploadFileMode 0600
-- Debug log configuration -------------------------------------------------
The default debug log configuration is to duplicate the error, warning
and notice messages from the error log.
SecDebugLog /var/log/nginx/modsecurity/debug.log
SecDebugLogLevel 0
-- Audit log configuration -------------------------------------------------
Log the transactions that are marked by a rule, as well as those that
trigger a server error (determined by a 5xx or 4xx, excluding 404,
level response status codes).
SecAuditEngine RelevantOnly
SecAuditLogRelevantStatus "^(?:5|4(?!04))"
Log everything we know about a transaction.
SecAuditLogParts ABIJDEFHZ
Use a single file for logging. This is much easier to look at, but
assumes that you will use the audit log only ocassionally.
SecAuditLogType Serial
SecAuditLogType Concurrent
SecAuditLog /var/log/nginx/modsecurity/modsec_audit.log
Specify the path for concurrent audit logging.
SecAuditLogStorageDir /var/log/nginx/modsecurity/
-- Miscellaneous -----------------------------------------------------------
Use the most commonly used application/x-www-form-urlencoded parameter
separator. There's probably only one application somewhere that uses
something else so don't expect to change this value.
SecArgumentSeparator &
Settle on version 0 (zero) cookies, as that is what most applications
use. Using an incorrect cookie version may open your installation to
evasion attacks (against the rules that examine named cookies).
SecCookieFormat 0
Specify your Unicode Code Point.
This mapping is used by the t:urlDecodeUni transformation function
to properly map encoded data to your language. Properly setting
these directives helps to reduce false positives and negatives.
SecUnicodeCodePage 20127
SecUnicodeMapFile unicode.mapping
Include csr/modsecurity_crs_10_setup.conf
Include csr/activated_rules/*.conf
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