Large-scale DDoS attacks disrupted Threema secure messaging service

Threema, a secure messaging service, was disrupted by large-scale distributed denial-of-service (DDoS) attacks that targeted both its infrastructure and its colocation partner, Nine. The attacks caused intermittent outages and service degradation for users in Switzerland, India, and China, despite internal status pages showing normal operations. The threat actor continuously changed attack patterns, making mitigation difficult, and an unrelated technical issue prevented timely status updates. Threema has since implemented specialized upstream DDoS protection to reduce future impact.

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