Key answers for CISOs.<\/strong><\/p>\n\n\n\n <\/p>\n\n\n\n This is the nature of major data breaches: they never remain confined to the organization that is directly affected. This information spreads and, when combined with other databases, fuels phishing campaigns, wire fraud attempts, and more. Those impacted by stolen data include individuals as well as companies and organizations. As a result, the right reflexes to adopt are almost the same, whether you are managing personal accounts or an information system with 5,000 workstations.<\/p>\n\n\n\n Major data breaches have become a global and highly public phenomenon. Cybercriminals \u2014 including new, younger, French\u2011speaking profiles \u2014 seek to pull off the \u201cbiggest hit\u201d possible and to make it known. Beyond notoriety, these groups may be driven by financial gain or, to a lesser extent, geopolitical motivations.<\/p>\n\n\n\n \u201cData breaches have become a mainstream issue. Public opinion is increasingly attentive to this type of risk.\u201d <\/p>\n <\/blockquote>\n <\/p>\n\n\n\n <\/p>\n\n<\/blockquote>\n\n\n\n Almost everyone today has personal data that has been exposed in a breach. The real challenge is therefore to identify which information has been compromised and which actions to take depending on the nature of this data:<\/p>\n\n\n\n The reflexes to adopt are the same for companies as for individuals, even though the stakes are naturally much higher in a collective structure. Social networks also deserve particular attention in a professional context, as information published on LinkedIn or other platforms can be combined with stolen data to fuel sophisticated social engineering attacks \u2014 whether identity theft, highly targeted phishing, or fraudulent phone calls.<\/p>\n\n\n\n In all cases, a breach at a supplier or purchasing group must trigger an immediate alert regarding the risk of phishing campaigns targeting the relevant teams. The bank must also be informed of the risks associated with compromised banking details (wire fraud or mandate fraud attempts).<\/p>\n\n\n\n Here is a checklist of priority actions for organizations and their members to know what to do in the event of data theft:<\/p>\n\n\n\n <\/p>\n\n\n\n <\/p>\n\n\n\n Since 2018, the GDPR has required organizations affected by a data breach to notify the CNIL and, in certain cases, the individuals concerned.<\/p>\n\n\n\n \u201cThis obligation has profoundly transformed practices: companies have generally improved their communication on the subject, and for the past two or three years, we can truly speak of an acceleration in transparency on these issues.\u201d <\/p>\n <\/blockquote>\n Communication formats vary: some remain very concise, others are more detailed and educational, but the overall trend is clearly toward greater transparency. This is a positive evolution: rapid and clear communication enables victims to adopt the right reflexes themselves without delay. Organizations that communicate effectively after a breach \u2014 explaining what was exposed, what was not, and what victims should do \u2014 not only limit the actual damage, but also preserve their long\u2011term reputation.<\/p>\n\n\n\n One direct consequence of the increased media coverage of data breaches is inevitably the multiplication of inquiries when an incident occurs. Nicolas Pley, Deputy Director of Risk Prevention at the Banque de France, describes a time\u2011consuming situation in which the CISO and CERT\u2011BDF are overwhelmed with questions and sources of varying quality across multiple internal conversations.<\/p>\n\n\n\n To move away from this reactive posture, Nicolas Pley set up an internal communication channel called \u201cCyberurgences,\u201d in which cyber teams provide concise answers to the following questions:<\/p>\n\n\n\n The idea is to proactively disseminate \u201cclean\u201d information to a selected group of internal readers who can, if they deem it necessary, cascade it to their teams. Beyond the obvious time savings, this approach also serves as a reminder for awareness\u2011raising. This strong example of internal communication \u2014 primarily between cyber teams and the Banque de France executive management \u2014 could easily be extended to a broader group of contributors. Indeed, sharing such information with a network of partners could help foster a virtuous ecosystem in which everyone knows whether they need to act and how.<\/p>\n\n\n\n \u201cThis initiative allowed us to regain control in the face of numerous, redundant, and insufficiently precise email chains. Thanks to this new channel, we have reduced the communication load around these breaches and now deliver a single, unified message, which is also clearer and more reassuring for teams.\u201d<\/p>\n <\/blockquote>\n <\/p>\n\n\n\n In conclusion, what should be done in the event of a massive data breach at a third party? For CISOs, it should be approached as an internal event. Every major public incident is an opportunity to test team responsiveness, verify the application of basic cyber hygiene rules, and remind everyone of the importance of separating professional and personal uses \u2014 while illustrating cyber risk<\/a> in a very concrete way.<\/strong><\/p>\n\n\n\nSetting the scene<\/strong><\/h2>\n\n\n\n
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Understanding what actually leaked<\/strong><\/h2>\n\n\n\n
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Data theft: what should be done?<\/h2>\n\n\n\n
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Communicating for compliance and trust<\/h2>\n\n\n\n
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The Banque de France initiative<\/h2>\n\n\n\n
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![\"Contact](\"https:\/\/www.advens.com\/app\/uploads\/2026\/03\/Advens-Interne-Signature-Mail-CERT.png\")
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