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We have Centos 6.4 server with a physical firewall. We keep seeing quite an number of PHP.CGI.Argument.Injection is detected by the firewall. On the server itself we have done the basic apache hardening as below. We are using fail2ban and also mod_secure. What else can be done to further harden the server?


    # This is the main Apache server configuration file.  It contains the
    # configuration directives that give the server its instructions.
    # See <URL:http://httpd.apache.org/docs/2.2/> for detailed information.
    # In particular, see
    # <URL:http://httpd.apache.org/docs/2.2/mod/directives.html>
    # for a discussion of each configuration directive.
    # Do NOT simply read the instructions in here without understanding
    # what they do.  They're here only as hints or reminders.  If you are unsure
    # consult the online docs. You have been warned.  
    # The configuration directives are grouped into three basic sections:
    #  1. Directives that control the operation of the Apache server process as a
    #     whole (the 'global environment').
    #  2. Directives that define the parameters of the 'main' or 'default' server,
    #     which responds to requests that aren't handled by a virtual host.
    #     These directives also provide default values for the settings
    #     of all virtual hosts.
    #  3. Settings for virtual hosts, which allow Web requests to be sent to
    #     different IP addresses or hostnames and have them handled by the
    #     same Apache server process.
    # Configuration and logfile names: If the filenames you specify for many
    # of the server's control files begin with "/" (or "drive:/" for Win32), the
    # server will use that explicit path.  If the filenames do *not* begin
    # with "/", the value of ServerRoot is prepended -- so "logs/foo.log"
    # with ServerRoot set to "/etc/httpd" will be interpreted by the
    # server as "/etc/httpd/logs/foo.log".

    ### Section 1: Global Environment
    # The directives in this section affect the overall operation of Apache,
    # such as the number of concurrent requests it can handle or where it
    # can find its configuration files.

    # Don't give away too much information about all the subcomponents
    # we are running.  Comment out this line if you don't mind remote sites
    # finding out what major optional modules you are running
    ServerTokens OS

    # ServerRoot: The top of the directory tree under which the server's
    # configuration, error, and log files are kept.
    # NOTE!  If you intend to place this on an NFS (or otherwise network)
    # mounted filesystem then please read the LockFile documentation
    # (available at <URL:http://httpd.apache.org/docs/2.2/mod/mpm_common.html#lockfile>);
    # you will save yourself a lot of trouble.
    # Do NOT add a slash at the end of the directory path.
    ServerRoot "/etc/httpd"

    # PidFile: The file in which the server should record its process
    # identification number when it starts.  Note the PIDFILE variable in
    # /etc/sysconfig/httpd must be set appropriately if this location is
    # changed.
    PidFile run/httpd.pid

    # Timeout: The number of seconds before receives and sends time out.
    Timeout 60

    # KeepAlive: Whether or not to allow persistent connections (more than
    # one request per connection). Set to "Off" to deactivate.
    KeepAlive Off

    # MaxKeepAliveRequests: The maximum number of requests to allow
    # during a persistent connection. Set to 0 to allow an unlimited amount.
    # We recommend you leave this number high, for maximum performance.
    MaxKeepAliveRequests 100

    # KeepAliveTimeout: Number of seconds to wait for the next request from the
    # same client on the same connection.
    KeepAliveTimeout 15

    ## Server-Pool Size Regulation (MPM specific)

    # prefork MPM
    # StartServers: number of server processes to start
    # MinSpareServers: minimum number of server processes which are kept spare
    # MaxSpareServers: maximum number of server processes which are kept spare
    # ServerLimit: maximum value for MaxClients for the lifetime of the server
    # MaxClients: maximum number of server processes allowed to start
    # MaxRequestsPerChild: maximum number of requests a server process serves
    <IfModule prefork.c>
    StartServers       8
    MinSpareServers    5
    MaxSpareServers   20
    ServerLimit      256
    MaxClients       256
    MaxRequestsPerChild  4000

    # worker MPM
    # StartServers: initial number of server processes to start
    # MaxClients: maximum number of simultaneous client connections
    # MinSpareThreads: minimum number of worker threads which are kept spare
    # MaxSpareThreads: maximum number of worker threads which are kept spare
    # ThreadsPerChild: constant number of worker threads in each server process
    # MaxRequestsPerChild: maximum number of requests a server process serves
    <IfModule worker.c>
    StartServers         4
    MaxClients         300
    MinSpareThreads     25
    MaxSpareThreads     75 
    ThreadsPerChild     25
    MaxRequestsPerChild  0

    # Listen: Allows you to bind Apache to specific IP addresses and/or
    # ports, in addition to the default. See also the <VirtualHost>
    # directive.
    # Change this to Listen on specific IP addresses as shown below to 
    # prevent Apache from glomming onto all bound IP addresses (
    Listen 80

    # Dynamic Shared Object (DSO) Support
    # To be able to use the functionality of a module which was built as a DSO you
    # have to place corresponding `LoadModule' lines at this location so the
    # directives contained in it are actually available _before_ they are used.
    # Statically compiled modules (those listed by `httpd -l') do not need
    # to be loaded here.
    # Example:
    # LoadModule foo_module modules/mod_foo.so
    #LoadModule auth_basic_module modules/mod_auth_basic.so
    #LoadModule auth_digest_module modules/mod_auth_digest.so
    #LoadModule authn_file_module modules/mod_authn_file.so
    #LoadModule authn_alias_module modules/mod_authn_alias.so
    #LoadModule authn_anon_module modules/mod_authn_anon.so
    #LoadModule authn_dbm_module modules/mod_authn_dbm.so
    #LoadModule authn_default_module modules/mod_authn_default.so
    #LoadModule authz_host_module modules/mod_authz_host.so
    #LoadModule authz_user_module modules/mod_authz_user.so
    #LoadModule authz_owner_module modules/mod_authz_owner.so
    #LoadModule authz_groupfile_module modules/mod_authz_groupfile.so
    #LoadModule authz_dbm_module modules/mod_authz_dbm.so
    LoadModule authz_default_module modules/mod_authz_default.so
    LoadModule ldap_module modules/mod_ldap.so
    LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
    LoadModule include_module modules/mod_include.so
    LoadModule log_config_module modules/mod_log_config.so
    LoadModule logio_module modules/mod_logio.so
    LoadModule env_module modules/mod_env.so
    LoadModule ext_filter_module modules/mod_ext_filter.so
    LoadModule mime_magic_module modules/mod_mime_magic.so
    LoadModule expires_module modules/mod_expires.so
    LoadModule deflate_module modules/mod_deflate.so
    LoadModule headers_module modules/mod_headers.so
    LoadModule usertrack_module modules/mod_usertrack.so
    LoadModule setenvif_module modules/mod_setenvif.so
    LoadModule mime_module modules/mod_mime.so
    #LoadModule dav_module modules/mod_dav.so
    LoadModule status_module modules/mod_status.so
    LoadModule autoindex_module modules/mod_autoindex.so
    LoadModule info_module modules/mod_info.so
    #LoadModule dav_fs_module modules/mod_dav_fs.so
    LoadModule vhost_alias_module modules/mod_vhost_alias.so
    #LoadModule negotiation_module modules/mod_negotiation.so
    LoadModule dir_module modules/mod_dir.so
    LoadModule actions_module modules/mod_actions.so
    #LoadModule speling_module modules/mod_speling.so
    LoadModule userdir_module modules/mod_userdir.so
    LoadModule alias_module modules/mod_alias.so
    #LoadModule substitute_module modules/mod_substitute.so
    LoadModule rewrite_module modules/mod_rewrite.so
    #LoadModule proxy_module modules/mod_proxy.so
    #LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
    #LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
    #LoadModule proxy_http_module modules/mod_proxy_http.so
    #LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
    #LoadModule proxy_connect_module modules/mod_proxy_connect.so
    LoadModule cache_module modules/mod_cache.so
    LoadModule suexec_module modules/mod_suexec.so
    LoadModule disk_cache_module modules/mod_disk_cache.so
    LoadModule cgi_module modules/mod_cgi.so
    LoadModule version_module modules/mod_version.so

    # The following modules are not loaded by default:
    #LoadModule asis_module modules/mod_asis.so
    #LoadModule authn_dbd_module modules/mod_authn_dbd.so
    #LoadModule cern_meta_module modules/mod_cern_meta.so
    #LoadModule cgid_module modules/mod_cgid.so
    #LoadModule dbd_module modules/mod_dbd.so
    #LoadModule dumpio_module modules/mod_dumpio.so
    #LoadModule filter_module modules/mod_filter.so
    #LoadModule ident_module modules/mod_ident.so
    #LoadModule log_forensic_module modules/mod_log_forensic.so
    #LoadModule unique_id_module modules/mod_unique_id.so

    # Load config files from the config directory "/etc/httpd/conf.d".
    Include conf.d/*.conf

    #ExtendedStatus On


    User apache
    Group apache

    ServerAdmin root@localhost       

    # If your host doesn't have a registered DNS name, enter its IP address here.
    # You will have to access it by its address anyway, and this will make 
    # redirections work in a sensible way.

    #ServerName http://********:80

    # ServerName directive.
    UseCanonicalName Off       

    DocumentRoot "/var/www/html"

    # First, we configure the "default" to be a very restrictive set of 
    # features.  
    <Directory />
        Options FollowSymLinks
        AllowOverride None

    <Directory "/var/www/html">

        Options -Indexes FollowSymLinks

        AllowOverride None

    # Controls who can get stuff from this server.
        Order allow,deny
        Allow from all

    # See also: http://httpd.apache.org/docs/misc/FAQ.html#forbidden
    <IfModule mod_userdir.c>

        UserDir disabled

        #UserDir public_html


    DirectoryIndex index.html index.html.var

    # AccessFileName: The name of the file to look for in each directory
    # for additional configuration directives.  See also the AllowOverride
    # directive.
    AccessFileName .htaccess

    # The following lines prevent .htaccess and .htpasswd files from being 
    # viewed by Web clients. 
    <Files ~ "^\.ht">
        Order allow,deny
        Deny from all
        Satisfy All

    # TypesConfig describes where the mime.types file (or equivalent) is
    # to be found.
    TypesConfig /etc/mime.types

    # a good value.  If most of your content is binary, such as applications
    # or images, you may want to use "application/octet-stream" instead to
    # keep browsers from trying to display binary files as though they are
    # text.
    DefaultType text/plain

    # contents of the file itself to determine its type.  The MIMEMagicFile
    # directive tells the module where the hint definitions are located.
    <IfModule mod_mime_magic.c>
    #   MIMEMagicFile /usr/share/magic.mime
        MIMEMagicFile conf/magic

    # nameserver.
    HostnameLookups Off

    #EnableMMAP off

    #EnableSendfile off

    ErrorLog logs/error_log

    LogLevel warn

    LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
    LogFormat "%h %l %u %t \"%r\" %>s %b" common
    LogFormat "%{Referer}i -> %U" referer
    LogFormat "%{User-agent}i" agent

    # "combinedio" includes actual counts of actual bytes received (%I) and sent (%O); this
    # requires the mod_logio module to be loaded.
    #LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio

    #CustomLog logs/access_log common

    # If you would like to have separate agent and referer logfiles, uncomment
    # the following directives.
    #CustomLog logs/referer_log referer
    #CustomLog logs/agent_log agent

    CustomLog logs/access_log combined

    # Set to "EMail" to also include a mailto: link to the ServerAdmin.
    # Set to one of:  On | Off | EMail
    ServerSignature Off

    # We include the /icons/ alias for FancyIndexed directory listings.  If you
    # do not use FancyIndexing, you may comment this out.
    Alias /icons/ "/var/www/icons/"

    <Directory "/var/www/icons">
        Options Indexes MultiViews FollowSymLinks
        AllowOverride None
        Order allow,deny
        Allow from all

    # WebDAV module configuration section.
    <IfModule mod_dav_fs.c>
        # Location of the WebDAV lock database.
        DAVLockDB /var/lib/dav/lockdb

    ScriptAlias /cgi-bin/ "/var/www/cgi-bin/"

    # "/var/www/cgi-bin" should be changed to whatever your ScriptAliased
    # CGI directory exists, if you have that configured.
    <Directory "/var/www/cgi-bin">
        AllowOverride None
        Options None
        Order allow,deny
        Allow from all

    IndexOptions FancyIndexing VersionSort NameWidth=* HTMLTable Charset=UTF-8

    AddIconByEncoding (CMP,/icons/compressed.gif) x-compress x-gzip

    AddIconByType (TXT,/icons/text.gif) text/*
    AddIconByType (IMG,/icons/image2.gif) image/*
    AddIconByType (SND,/icons/sound2.gif) audio/*
    AddIconByType (VID,/icons/movie.gif) video/*

    AddIcon /icons/binary.gif .bin .exe
    AddIcon /icons/binhex.gif .hqx
    AddIcon /icons/tar.gif .tar
    AddIcon /icons/world2.gif .wrl .wrl.gz .vrml .vrm .iv
    AddIcon /icons/compressed.gif .Z .z .tgz .gz .zip
    AddIcon /icons/a.gif .ps .ai .eps
    AddIcon /icons/layout.gif .html .shtml .htm .pdf
    AddIcon /icons/text.gif .txt
    AddIcon /icons/c.gif .c
    AddIcon /icons/p.gif .pl .py
    AddIcon /icons/f.gif .for
    AddIcon /icons/dvi.gif .dvi
    AddIcon /icons/uuencoded.gif .uu
    AddIcon /icons/script.gif .conf .sh .shar .csh .ksh .tcl
    AddIcon /icons/tex.gif .tex
    AddIcon /icons/bomb.gif core

    AddIcon /icons/back.gif ..
    AddIcon /icons/hand.right.gif README
    AddIcon /icons/folder.gif ^^DIRECTORY^^
    AddIcon /icons/blank.gif ^^BLANKICON^^

    # DefaultIcon is which icon to show for files which do not have an icon
    # explicitly set.
    DefaultIcon /icons/unknown.gif

    # HeaderName is the name of a file which should be prepended to
    # directory indexes. 
    ReadmeName README.html
    HeaderName HEADER.html

    # IndexIgnore is a set of filenames which directory indexing should ignore
    # and not include in the listing.  Shell-style wildcarding is permitted.
    IndexIgnore .??* *~ *# HEADER* README* RCS CVS *,v *,t

    # * being a certain language than marking it with the wrong
    # * language!
    DefaultLanguage english

    # Simplified Chinese (zh-CN) - Spanish (es) - Traditional Chinese (zh-TW)
    AddLanguage ca .ca
    AddLanguage cs .cz .cs
    AddLanguage da .dk
    AddLanguage de .de
    AddLanguage el .el
    AddLanguage en .en
    AddLanguage eo .eo
    AddLanguage es .es
    AddLanguage et .et
    AddLanguage fr .fr
    AddLanguage he .he
    AddLanguage hr .hr
    AddLanguage it .it
    AddLanguage ja .ja
    AddLanguage ko .ko
    AddLanguage ltz .ltz
    AddLanguage nl .nl
    AddLanguage nn .nn
    AddLanguage no .no
    AddLanguage pl .po
    AddLanguage pt .pt
    AddLanguage pt-BR .pt-br
    AddLanguage ru .ru
    AddLanguage sv .sv
    AddLanguage zh-CN .zh-cn
    AddLanguage zh-TW .zh-tw

    LanguagePriority en ca cs da de el eo es et fr he hr it ja ko ltz nl nn no pl pt pt-BR ru sv zh-CN zh-TW

    ForceLanguagePriority Prefer Fallback

    AddDefaultCharset UTF-8

    # AddType allows you to add to or override the MIME configuration
    # file mime.types for specific file types.
    #AddType application/x-tar .tgz

    # AddEncoding allows you to have certain browsers uncompress
    # information on the fly. Note: Not all browsers support this.
    #AddEncoding x-compress .Z
    #AddEncoding x-gzip .gz .tgz

    # If the AddEncoding directives above are commented-out, then you
    # probably should define those extensions to indicate media types:
    AddType application/x-compress .Z
    AddType application/x-gzip .gz .tgz

    #   MIME-types for downloading Certificates and CRLs
    AddType application/x-x509-ca-cert .crt
    AddType application/x-pkcs7-crl    .crl

    # AddHandler allows you to map certain file extensions to "handlers":
    # actions unrelated to filetype. These can be either built into the server
    # or added with the Action directive (see below)
    # To use CGI scripts outside of ScriptAliased directories:
    # (You will also need to add "ExecCGI" to the "Options" directive.)
    #AddHandler cgi-script .cgi

    # For files that include their own HTTP headers:
    #AddHandler send-as-is asis

    # For type maps (negotiated resources):
    # (This is enabled by default to allow the Apache "It Worked" page
    #  to be distributed in multiple languages.)
    AddHandler type-map var

    # Filters allow you to process content before it is sent to the client.
    # To parse .shtml files for server-side includes (SSI):
    # (You will also need to add "Includes" to the "Options" directive.)
    AddType text/html .shtml
    AddOutputFilter INCLUDES .shtml

    # Action lets you define media types that will execute a script whenever
    # Format: Action media/type /cgi-script/location
    # Format: Action handler-name /cgi-script/location

    # Some examples:
    #ErrorDocument 500 "The server made a boo boo."
    #ErrorDocument 404 /missing.html
    #ErrorDocument 404 "/cgi-bin/missing_handler.pl"
    #ErrorDocument 402 http://www.example.com/subscription_info.html

    # Putting this all together, we can internationalize error responses.
    # We use Alias to redirect any /error/HTTP_<error>.html.var response to
    # our collection of by-error message multi-language collections.  We use 
    # includes to substitute the appropriate text.
    # You can modify the messages' appearance without changing any of the
    # default HTTP_<error>.html.var files by adding the line:
    #   Alias /error/include/ "/your/include/path/"
    # which allows you to create your own set of files by starting with the
    # /var/www/error/include/ files and
    # copying them to /your/include/path/, even on a per-VirtualHost basis.

    Alias /error/ "/var/www/error/"

    <IfModule mod_negotiation.c>
    <IfModule mod_include.c>
        <Directory "/var/www/error">
            AllowOverride None
            Options IncludesNoExec
            AddOutputFilter Includes html
            AddHandler type-map var
            Order allow,deny
            Allow from all
            LanguagePriority en es de fr
            ForceLanguagePriority Prefer Fallback

    #    ErrorDocument 400 /error/HTTP_BAD_REQUEST.html.var
    #    ErrorDocument 401 /error/HTTP_UNAUTHORIZED.html.var
    #    ErrorDocument 403 /error/HTTP_FORBIDDEN.html.var
    #    ErrorDocument 404 /error/HTTP_NOT_FOUND.html.var
    #    ErrorDocument 405 /error/HTTP_METHOD_NOT_ALLOWED.html.var
    #    ErrorDocument 408 /error/HTTP_REQUEST_TIME_OUT.html.var
    #    ErrorDocument 410 /error/HTTP_GONE.html.var
    #    ErrorDocument 411 /error/HTTP_LENGTH_REQUIRED.html.var
    #    ErrorDocument 412 /error/HTTP_PRECONDITION_FAILED.html.var
    #    ErrorDocument 413 /error/HTTP_REQUEST_ENTITY_TOO_LARGE.html.var
    #    ErrorDocument 414 /error/HTTP_REQUEST_URI_TOO_LARGE.html.var
    #    ErrorDocument 415 /error/HTTP_UNSUPPORTED_MEDIA_TYPE.html.var
    #    ErrorDocument 500 /error/HTTP_INTERNAL_SERVER_ERROR.html.var
    #    ErrorDocument 501 /error/HTTP_NOT_IMPLEMENTED.html.var
    #    ErrorDocument 502 /error/HTTP_BAD_GATEWAY.html.var
    #    ErrorDocument 503 /error/HTTP_SERVICE_UNAVAILABLE.html.var
    #    ErrorDocument 506 /error/HTTP_VARIANT_ALSO_VARIES.html.var


    # The following directives modify normal HTTP response behavior to
    # handle known problems with browser implementations.
    BrowserMatch "Mozilla/2" nokeepalive
    BrowserMatch "MSIE 4\.0b2;" nokeepalive downgrade-1.0 force-response-1.0
    BrowserMatch "RealPlayer 4\.0" force-response-1.0
    BrowserMatch "Java/1\.0" force-response-1.0
    BrowserMatch "JDK/1\.0" force-response-1.0

    # The following directive disables redirects on non-GET requests for
    # a directory that does not include the trailing slash.  This fixes a 
    # problem with Microsoft WebFolders which does not appropriately handle 
    # redirects for folders with DAV methods.
    # Same deal with Apple's DAV filesystem and Gnome VFS support for DAV.
    BrowserMatch "Microsoft Data Access Internet Publishing Provider" redirect-carefully
    BrowserMatch "MS FrontPage" redirect-carefully
    BrowserMatch "^WebDrive" redirect-carefully
    BrowserMatch "^WebDAVFS/1.[0123]" redirect-carefully
    BrowserMatch "^gnome-vfs/1.0" redirect-carefully
    BrowserMatch "^XML Spy" redirect-carefully
    BrowserMatch "^Dreamweaver-WebDAV-SCM1" redirect-carefully
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up vote 1 down vote accepted

Penetration Testing

When maintaining a server that's accessible to the internet you really can't escape the need to perform penetration testing (aka. pentesting) yourself. I typically use the following tools to do this:

  • OpenVAS is a framework of several services and tools offering a comprehensive and powerful vulnerability scanning and vulnerability management solution. (Free/Opensource)
  • Nessus is a proprietary comprehensive vulnerability scanner which is developed by Tenable Network Security. It is free of charge for personal use in a non-enterprise environment. Its goal is to detect potential vulnerabilities on the tested systems.
  • Metasploit Framework is a tool for developing and executing exploit code against a remote target machine.

NSA Hardening Guide

I typically go through this guide when setting up a CentOS system. It's specific to RHEL5 but everything in the guide is relevant and should be adhered to. It does specifically discuss hardening Apache.


As you're doing now, review any anomalies and follow up on them and make sure you understand them so that you can weigh whether they're a potential vector for your setup or not.

Eric Romang's Blog is a pretty good resource for looking these vulnerabilities up. Specifically here's the exploit you're noticing: CVE-2012-1823 PHP CGI Argument Injection Metasploit Demo. You can also look up the vulnerabilities in these 2 databases:

  • OSVDB - Open Sourced Vulnerability Database
  • CVE - Common Vulnerabilities and Exposures List
share|improve this answer
infact I am new into all this hardening skills trying to learn and beef yes I always try to monitor and learn and further hardening. I have actually downloaded kali linux which already have metaspoilt and open vas in it. I just dont know how to start the penetration test too lost and good guide beside their website. I am also looking into some youtube video. Which one from your experience I should start to work on first open vas? – biz14 Jul 24 '13 at 4:07
@biz14 - I would start with openvas. Once you set it up it's web based to direct it to start a scan, and review the results of scans. – slm Jul 24 '13 at 4:54
I started first with openvas-setup and this all came out towards the end. Stopping OpenVAS Manager: openvasmd. Stopping OpenVAS Scanner: openvassd. All plugins loaded Starting OpenVAS Scanner: openvassd. Starting OpenVAS Manager: openvasmd. Restarting OpenVAS Administrator: openvasad. Restarting Greenbone Security Assistant: gsad. Enter password: ad main:MESSAGE:30553:2002-01-01 00h34.24 UTC: No rules file provided, the new user will have no restrictions. ad main:MESSAGE:30553:2002-01-01 00h34.24 UTC: User admin has been successfully created. – biz14 Jul 24 '13 at 10:48
Next went to setup openvas-gsd I try to login but then I read at the site it says this "Note: that the scan engine must have OMP support enabled for the given port for a successful connection? What should I do here? Thank you. – biz14 Jul 24 '13 at 10:49
@biz14 - you need to start the service /etc/init.d/openvas-manager. Are you following a tutorial? Can you provide the URL if so. We're getting into things that are beyond the scope of your question. – slm Jul 24 '13 at 11:50

The PHP.CGI.Argument.Injection exploit allows remote code execution on PHP if used as a CGI and if version <= 5.3.12 or <= 5.4.2.

Your seeing those lines in the firewall's logs does not mean that you're vulnerable, only that someout out there thinks that you might be. To that effect, but that is only my opinion and I had several experts disagree vehemently, having your server hide its versioning tokens might be counterproductive, because would-be exploiters will try all their tricks - those you might be vulnerable to, and those you aren't. If an exploit against FooScript comes out, you won't be spared just because you aren't advertising your usage of FooScript.

So, what you can do (and I suppose you already did) is run PHP as a module and/or update it to be a later version than the vulnerable ones. Once you are no longer vulnerable you might want to instruct the firewall to drop that kind of attempts with no warning (of course you still want to be warned about other attempts!).

In general, you may also want to check out one or more vulnerability scanners.

On PHP as a module or CGI

PHP can be installed in various ways. As a module (mod_php5), it "lives" within the Apache process, by default with the same rights. You could think of it as a PHP capability that gets "embedded" inside Apache, making it "smarter". To compromise mod_php might mean to compromise Apache (there are remedial measures, but still), and therefore all of its web sites. As a CGI, it lives as a separate process (several separate process), which is thought by some to be more secure, while other observe it is less performant (every call has to setup the whole process anew). FastCGI is somewhere in the middle, but requires more configuration; there are two or three flavours of it.

The configuration looks OK; you may want to change these values, though:

KeepAlive      On
DefaultType    text/html
EnableMMAP     On

mmap'ing can increase performances with next to no cost. There are some caveats, but they are usually not relevant (you'll check whether this is your case, of course):

This memory-mapping sometimes yields a performance improvement. But in some environments, it is better to disable the memory-mapping to prevent operational problems:

On some multiprocessor systems, memory-mapping can reduce the performance of the httpd.
Deleting or truncating a file while httpd has it memory-mapped can cause httpd to crash with a segmentation fault.

Disabling Keep-Alive may mitigate some kind of (D)DoS - see the security tips -, but it is usually best to adopt other measures instead, like banning (as you already do), and this makes disabling Keep-Alives largely superfluous; while having them enables enhances performances for "good" clients (also freeing resources to deal with bad ones).

The default content-type of text/html isn't really relevant, but I feel that there is little reason to have your average web server default to plain text.

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any comments on how I have harden my httpd.conf? Anythere I should be doing? What do you mean run php as a module ? The problem when I run yum update it never update my php so looks like I got to manually install but I am worried it will break Centos's stability? – biz14 Jul 23 '13 at 18:16
Added to answer. As regards yum update, verify that php has been installed through yum. But I seem to remember that only minor-minor version updates are automatic, the others can impact compatibility and you have to do them yourself by yumming the appropriate package, e.g. php54 or php55. But check yourself, I might remember wrong (I usually use zypper under OpenSuSE, it's been some time since I worked on a CentOS). – lserni Jul 23 '13 at 20:20
@Iserni according to Centos they normall backport and it seems and the current version PHP 5.3.3 is secured and protect with this backport methodology so I guess is patched and secured then. This sharing for the benefits of the rest who are having issues like me. – biz14 Jul 24 '13 at 4:17

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