Attacker phished way into US defense supplier's Microsoft 365 account

US defense and aerospace supplier IEH Corporation 'fessed up that a criminal managed to break into its Microsoft 365 mailbox in a filing with regulators. In a Form 8-K filed with the Securities and Exchange Commission on Thursday, IEH said one of its staffers fell for a phishing scam that gave an attacker access to its M365 environment. The attacker "impersonated a prospective business contact" and sent the employee what appeared to be a genuine Microsoft sharing link. The accompanying fake login page duly harvested the victim's M365 credentials. "The threat actor gained access to mailbox contents, including email messages, attachments, customer communications, purchase orders, engineering-related documentation, and potentially export-controlled technical information," IEH said in the SEC filing [PDF]. IEH said it had found "no evidence" that the information was copied or exfiltrated, although it was accessible to the intruder during the "compromise period." IEH said it discovered the intrusion on August 4 but did not disclose when the compromised account was first accessed or how long the intruder remained inside. "The account was secured, malicious mailbox rules were disabled, evidence was preserved, and corrective actions are underway," it said. "Following containment and investigation activities, the company initiated a review of account security controls and authentication protections applicable to Microsoft 365 services." The incident has not disrupted operations, and IEH does not expect it to have a material impact, although the investigation continues. The absence of detected exfiltration does not mean the intruder merely browsed the inbox and left. Compromised mailboxes can be used to monitor communications, impersonate employees, redirect payments, or prepare follow-on attacks, while data theft is not always visible in Microsoft 365 logs. There is not enough information to attribute the attack. IEH's work for defense and aerospace customers could make it an attractive espionage target, but ordinary cybercriminals also compromise mailboxes for fraud and data theft. Both Russia and China have been caught snooping around US orgs for defense-related information in the past year, although there is nothing to suggest either was behind the attack on IEH. Brooklyn-based IEH makes hyperboloid connectors designed for harsh and high-stress environments. Its components are used in printed circuit boards, medical devices, commercial aircraft, fighter jets, missiles, satellites, and other systems. Some of the high profile US programs that use IEH's hyperboloid connectors include the PATRIOT air-defense system, AMRAAM, THAAD, the APKWS precision-guided rocket, and the MARK-48 torpedo. ®