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 Topic: Stopping GET request flooding |
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| Author |
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santa.klaus
Joined: 11 Feb 2013
Posts: 5
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 Posted: Tue 12 Feb '13 4:05 Post subject: Stopping GET request flooding |
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Hello apacheloungies,
I'm experiencing many GET requests in the access.log on my server. I've tried to prevent this requests with mod_security but it's not working. Have you any hint how I can manage to deny this requests?
Here is a dump from the access.log:
| Code: | 201.232.48.212 - - [12/Feb/2013:02:51:53 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&rnd=80009970&p=10000001 HTTP/1.0" 301 316
200.75.69.57 - - [12/Feb/2013:02:51:53 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&retry=1&rnd=425798936&p=10000002 HTTP/1.0" 301 329
201.232.48.212 - - [12/Feb/2013:02:51:53 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&retry=1&rnd=245114880&p=10000002 HTTP/1.0" 301 329
200.75.69.57 - - [12/Feb/2013:02:52:10 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&rnd=213537933&p=10000001 HTTP/1.0" 301 317
200.75.69.57 - - [12/Feb/2013:02:52:10 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&retry=1&rnd=379135632&p=10000002 HTTP/1.0" 301 329
201.232.48.212 - - [12/Feb/2013:02:52:12 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&rnd=197702418&p=10000001 HTTP/1.0" 301 317
201.232.48.212 - - [12/Feb/2013:02:52:12 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&retry=1&rnd=197702418&p=10000002 HTTP/1.0" 301 329
200.75.69.57 - - [12/Feb/2013:02:52:27 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&rnd=506118500&p=10000001 HTTP/1.0" 301 317
200.75.69.57 - - [12/Feb/2013:02:52:27 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&retry=1&rnd=165879798&p=10000002 HTTP/1.0" 301 329
201.232.48.212 - - [12/Feb/2013:02:52:30 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&rnd=149894745&p=10000001 HTTP/1.0" 301 317
201.232.48.212 - - [12/Feb/2013:02:52:30 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&retry=1&rnd=149894745&p=10000002 HTTP/1.0" 301 329
200.75.69.57 - - [12/Feb/2013:02:52:44 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&rnd=292596150&p=10000001 HTTP/1.0" 301 317
200.75.69.57 - - [12/Feb/2013:02:52:44 +0100] "GET /din.aspx?s=00000000&id=677203362&client=DynGate&retry=1&rnd=459401982&p=10000002 HTTP/1.0" 301 329
201.232.48.212 - - [12/Feb/2013:02:52:47 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&rnd=443746744&p=10000001 HTTP/1.0" 301 317
201.232.48.212 - - [12/Feb/2013:02:52:47 +0100] "GET /din.aspx?s=00000000&id=118465483&client=DynGate&retry=1&rnd=101729728&p=10000002 HTTP/1.0" 301 329 |
It's about 500 of such requests in 10 minutes. I've activated mod_security. The server loads following default modsecurity.conf with an additional SecRule for my problem on the bottom. But the requests are still logged with a 301 in the access.log.
| Quote: | # -- 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 On
# -- 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
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,status:44,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 On
# 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 C:/web/tmp/
# 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 C:/web/tmp/
# -- 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 /opt/modsecurity/var/upload/
# 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 /opt/modsecurity/var/log/debug.log
#SecDebugLogLevel 3
# -- 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
SecAuditLog logs/modsec_audit.log
# Specify the path for concurrent audit logging.
#SecAuditLogStorageDir /opt/modsecurity/var/audit/
# -- 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
# --------------------------------------------------------------------------------------------------------------------------------
# --------------------------------------------------------------------------------------------------------------------------------
#SecDefaultAction log,auditlog,deny,status:406,phase:2,\
SecRule QUERY_STRING "/din.aspx" nolog,deny,status:406
#SecRule REQUEST_HEADERS:Host "^[\d\.]+$" \ "phase:1,t:none,block,msg:'Host is an IP address'" |
I'm using Apache 2.4.3 x64 with PHP 5.4.9 x64 on Windows Server 2008 R2.
After searching I found that this requests belong to some Teamviewer stuff. But I never had it installed on the server. I was afraid that my server could have been compromised. But only an up-to-date wordpress application and roundcube are currently installed on this system along with Immunet 3.0 antivirus, that found nothing after a full system scan.
What can I do?
Best Regards
Klaus |
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tdonovan
Moderator
Joined: 17 Dec 2005
Posts: 611
Location: Milford, MA, USA
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| Posted: Tue 12 Feb '13 21:32 Post subject: |
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Your mod_security rule doesn't seem quite right: | Code: | | SecRule QUERY_STRING "/din.aspx" nolog,deny,status:406 |
Did you mean REQUEST_FILENAME (the part of the URI before the ? character) instead of QUERY_STRING (the part after the ? character)?
Also, response code 403 indicates that the client should not retry. This may be a better response to send than 406.
Perhaps this mod_security rule would work better for you: | Code: | | SecRule REQUEST_FILENAME "^/din.aspx" nolog,deny,status:403 |
-tom- |
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santa.klaus
Joined: 11 Feb 2013
Posts: 5
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| Posted: Wed 13 Feb '13 1:55 Post subject: |
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Thanks for this help!!!
REQUEST_FILENAME is actually more appropriate. I'll give it a try.
EDIT:
It seems to work, but both mod_security and access.log are logging. The SecRule has the "nolog" action. Why does mod_security still log it? Can I exclude this requests from access.log? |
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