TLDR:More than 100 million records were exposed in October through leaks at firms and institutions.Binance lost $6.3 billion from hot wallets, while CryptoBilis and CoinDCX also reported thefts. A weak eMudhra certificate key and two critical PHP bugs exposed core web infrastructure to attackers. CERT-In reported unauthorized AI agent access to live systems, and major US banks began blocking agents. Black October is the name security researchers have given to the past month in cyberspace. Attackers exposed more than 100 million records and knocked hospitals and local governments offline. Critical flaws also surfaced in widely used software. The month ended with $6.3 billion stolen from Binance hot wallets.Most attacks relied on access that was already trusted, such as vendors, cloud logins, certificates, and old systems. Three crypto incidents were reported in the last week of the month.Black October Began With Large Data Leaks and Software FlawsIn a post on X, Bull Theory listed the major incidents of Black October. Ransomware reached the University of Illinois Chicago College of Medicine. Yakiniku King leaked 10.79 million member records. Denmark’s CPR register also saw 8.8 million identity records accessed without authorization. October 2026 was one of the most terrifying months cyberspace has ever seen. Security researchers are already calling it "Black October."Tens of millions of people had their personal data exposed. Critical flaws were found in software that most of the internet runs on.… pic.twitter.com/kzS9tH6vAH— Bull Theory (@BullTheoryio) October 31, 2026A ransomware attack on IDCF Cloud disrupted services for 495 companies and local governments in Japan. Sourcenext reported 22.52 million customer records potentially exposed. Burger King Japan and Capcom followed with 11.18 million and 11.77 million records. Leaked names, emails, and ID numbers are often used in scam emails and fake login pages.Software flaws added to the problem. On October 17, researchers found that private keys behind eight eMudhra certificates were weak enough to be worked out. eMudhra’s shares fell about 20%, and the company is leaving the global SSL certificate business.PHP also released emergency fixes on October 21 for two critical bugs. The flaws let attackers take over web servers without a password. PHP runs on about 70% of web servers. The US government later confirmed active exploitation and ordered federal agencies to patch within three days.AI Agents, Emergency Guidance, and Crypto Thefts FollowedAI agents added another risk during Black October. On October 15, India’s CERT-In warned that AI agents accessed live systems at Indian organizations without authorization. The agents reached personal data and confidential business records.In the US, JPMorgan, Morgan Stanley, and Charles Schwab have started blocking outside AI agents from customer accounts. Governments are also preparing for system failures. On October 22, the UK launched its Be Ready campaign. It advises people to keep at least three days of food and water at home. Germany advises up to 10 days, while Sweden, Norway, and Estonia suggest at least 7 days.The final week brought further attacks. A cyberattack on University of New Mexico Health disrupted appointments and forced ambulance diversions. Florida’s Department of Education reported up to 4.9 million people potentially affected.Crypto platforms were also targeted. CryptoBilis reportedly lost up to $93 million through tampered hardware wallets. CoinDCX lost nearly $16 million through compromised legacy wallet infrastructure. Binance lost $6.3 billion from compromised hot wallets, among the biggest crypto hacks on record. Bull Theory noted that one compromised wallet can put billions at risk during Black October.The post Black October Cyberattacks: Binance Hack Caps Month of Massive Data Breaches appeared first on Blockonomi.