CERN Computer Security Information

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <link rel="stylesheet" href="/style.css" type="text/css" /> <script type="text/javascript" src="/jquery.min.js"></script> <title>CERN Computer Security Information</title> <script type="text/javascript"> $(document).ready(function(){ // Menu highlight var path = location.pathname.split("/"); if ( path ) { $('#main_menu a[href*="' + path[1] + '"][class!="noselect"]').addClass('selected'); // path[3] = /security/<xxxxx>/ $('#sidebar ul.sidemenu li[class!="noselect"]:has(a[href$="' + path.reverse()[0] + '"])').addClass('selected'); } // Add icon to external links $('a[id!=logo-img]').filter(function() { return this.hostname && this.hostname !== location.hostname; }).after(' <img src="/images/external_link.png" alt="external link" title="external link"/>'); }); </script> </head> <body> <div id="wrap"> <div id="top-bg"></div>  <div id="header"> <div id="logo-text"> <a id="logo-img" href="https://home.cern/"><img src="/images/CERNLogo2.png" width="59" height="59" style="margin: 10px" alt="CERN Logo"/></a><div id="logo-text-big"><a href="/home/en/index.shtml" title="">CERN Computer Security</a></div> </div> <div id="header-logo"><a href="/services/en/emergency.shtml"><img width=335 src="/images/emergency.png" alt="Computer Emergencies"/></a></div> </div>  <div id="header-photo"></div>  <div id="nav"> <ul id="main_menu"> <li><a class="noselect" href="/home/fr/index.shtml"><img src="/images/fr.png" alt="FR"/></a></li> <li><a href="/home/en/index.shtml">Home</a></li> <li><a href="/rules/en/index.shtml">Computing Rules</a></li> <li><a href="/recommendations/en/index.shtml">Recommendations</a></li> <li><a href="/training/en/index.shtml">Training</a></li> <li><a href="/services/en/index.shtml">Services</a></li> <li><a class="secured" href="/reports/en/index.shtml">Reports & Presentations</a></li> </ul> </div>   <div id="content-wrap"> <div id="main"> <h2>Securing Web Applications</h2> <p>Since Web applications are usually exposed to potentially untrusted users, their developers should take extra care for securing them. The number one vulnerability on Web applications is putting too much trust in the clients/users. Clients might be malicious and pass unanticipated input to Web applications making them misbehave. If there is one main piece of advice, it is:</p> <p> <center> <table> <tr> <th><b>Do not trust any user input !</a></b></th> </tr> </table> </center> </p> <p>This means checking the correctness of all data/values that come from the client site (script arguments/form fields, cookies, header fields like user-agent or referer etc.). They all need to be validated, and sanitized before being used. Additionally, when printing out user input values back to the client, or using them for accessing external systems like a database, these values need to be correctly escaped.</p> <p><center><img border="0" src="/recommendations/images/command_injection.png" width="100%"></center></p> <p>If you develop Web applications at CERN, <b>you are strongly encouraged to attend (for free) <a href="/training/en/technical.shtml#sw">"Developing secure software"</a> course</b>. The last part of the course is dedicated to Web application security: typical vulnerabilities are demonstrated, and ways to avoid them are discussed.</p>  <p>Some other materials worth having a look:</p> <ul> <li> <a href="http://indico.cern.ch/getFile.py/access?contribId=120&sessionId=59&resId=0&materialId=slides&confId=18714"> Web Applications Security</a> by Romain Wartel, CERN and EGEE/OSCT</li> <li> <a href="http://indico.cern.ch/getFile.py/access?contribId=16&sessionId=3&resId=1&materialId=slides&confId=29134"> CSRF etc.</a> by Andrew McNab, Univ of Manchester</li> </ul> </div>    <div id="sidebar"> <h3>For All Users<br/> (Experts or Not)</h3> <ul class="sidemenu"> <li><a href="/recommendations/en/good_practises.shtml">Seven easy good practises</a></li> <li><a href="/recommendations/en/how_to_secure_your_pc.shtml">How to secure your PC or Mac</a></li> <li><a href="/recommendations/en/passwords.shtml">Passwords & toothbrushes</a></li> <li><a href="/recommendations/en/2FA.shtml">Starting with multi-factor authentication</a></li> <li><a href="/recommendations/en/bad_mails.shtml">Bad mails for you:<br/>"Phishing", "SPAM" & fraud</a></li> <li><a href="/recommendations/en/malicious_email.shtml">How to identify malicious e-mails and attachments</a></li> <li><a href="/recommendations/en/how_to_remove_malicious_browser_notifications.shtml">How to remove malicious browser notifications</a></li> <li><a href="/recommendations/en/working_remotely.shtml">Working remotely</a></li> <li><a href="/recommendations/en/connecting_to_cern.shtml">Connecting to CERN</a></li> <li><a href="/recommendations/en/ssh.shtml">Connecting using SSH</a></li> </ul> <h3>For Software Developers</h3> <ul class="sidemenu"> <li>Good programming in <a href="/recommendations/en/program_c.shtml">C/C++</a>, <a href="/recommendations/en/program_java.shtml">Java</a>, <a href="/recommendations/en/program_perl.shtml">Perl</a>, <a href="/recommendations/en/program_php.shtml">PHP</a>, and <a href="/recommendations/en/program_python.shtml">Python</a></li> <li><a href="/recommendations/en/password_alternatives.shtml">How to keep secrets secret<br/> (alternatives to passwords)</a></li> <li><a href="/recommendations/en/checklist_for_coders.shtml">Security checklist</a></li> <li><a href="https://gitlab.docs.cern.ch/docs/Secure%20your%20application/">GitLab CI Security Tools</a></li> <li><a href="/recommendations/en/web_applications.shtml">Securing Web applications</a></li> <li><a href="/recommendations/en/code_tools.shtml">Static code analysis tools</a></li> <li><a href="/recommendations/en/more_on_software.shtml">Further reading</a></li> </ul> <h3>For System Owners</h3> <ul class="sidemenu"> <li><a href="/recommendations/en/rootkits.shtml">Checking for rootkits</a></li> <li><a href="https://twiki.cern.ch/twiki/bin/viewauth/CNIC/WebHome">Securing Control Systems (CNIC)</a></li> <li><a href="/recommendations/en/containers.shtml">Securing Containers & Pods</a></li> <li><a href="/rules/en/baselines.shtml">Security baselines</a></li> <li><a href="http://linux.web.cern.ch/linux/docs/linux_exploit_faq.shtml"> The CERN Linux vulnerability FAQ</a></li> </ul> </div>   </div>  <div id="footer-wrap"> <div id="footer-bottom"> © Copyright 2024<strong> <a href="https://cern.ch/security">CERN Computer Security Office</a></strong> <table> <tr> <td id="footer-info-left"> e-mail: <a href="mailto:Computer.Security@cern.ch">Computer.Security@cern.ch</a><br/> Please use the following PGP key to encrypt your messages:<br/> ID: 0x954CE234B4C6ED84<br/> <a href="https://keys.openpgp.org/vks/v1/by-fingerprint/429D60460EBE8006B04CDF02954CE234B4C6ED84">429D 6046 0EBE 8006 B04C DF02 954C E234 B4C6 ED84</a> </td> <td id="footer-info-right"> Phone: +41 22 767 0500<br/> Please listen to the recorded instructions. </td> </tr> </table> </div> </div>  </div>   </body> </html>

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CERN Computer Security Information