CERN Computer Security Information

锘匡豢<!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; 聽 }).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>How to remove malicious browser notifications</h2> <p> A "browser notification scam" involves fraudulent messages that mimic genuine alerts from arbitrary websites. These deceptive tactics trick users into clicking on links which may lead them to dangerous sites, phishing attempts or malware downloads. The notifications typically resemble authentic pop-ups like system or app updates, subscription (re)confirmations, or enticing deals, making it difficult for the user to discern their false nature. </p> <h4>Removing malicious browser notifications</h4> <ol> <li>Block notifications:<ul><li>Review and revoke notification permissions for non-approved websites;</li><li>Consider disabling notifications globally and only allowing them for trusted sites:</li></ul></li> <img src="../images/disable_notifications.png" width="500"><p></p> <li>Clear browser data for each affected browser:<ul><li>Clear all cookies and site data;</li><li>Clear the browser cache;</li><li>Remove all saved passwords.</li></ul></li> <li>Review your so-called "service worker" background tasks and unregister all suspicious service workers (note: some service workes might be used for ligit usecases like browser extensions): <ul><li>Open the browser's developer tools (that can be done by pressing the F12 on your keyboard for most browsers);</li><li>Go to the Application tab;</li><li>Under "Service Workers", find and unregister the malicious worker:</li></ul></li> <img src="../images/unregister_service_worker.png" width="500"><p></p> <li>Ensure keeping browsers up-to-date as they are known to be a vector for many attacks and review extensions:<ul><li>Audit and remove any suspicious browser extensions;</li><li>Install a reputable ad blocking extension such as <a href="https://ublockorigin.com/" target="_new">uBlock Origin</a> (many threats are coming nowadays via malvertisements that ad blockers are quite good at blocking);</li><li>Malicious extensions pose a much bigger threat due to their broader access and permissions, including cross-site data access and persistent background scripts.</li></ul></li> <li>Check for persistence, i.e. look for any unexpected startup items or scheduled tasks that might be reinstalling the service worker;</li> <li>...and remain aware: Allowing notifications and installing extensions from untrusted sources pose significant security and privacy risks.</li> </ol> <p>The above instructions have been modelled based on the remediation steps from <a href="https://gosecure.ai/wp-content/uploads/Anatomy-of-Service-Worker-Abuse-From-Visit-to-Network-Anomaly.pdf" target="_new">https://gosecure.ai/wp-content/uploads/Anatomy-of-Service-Worker-Abuse-From-Visit-to-Network-Anomaly.pdf</a></p> </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> 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CERN Computer Security Information