Network Security

LLMNR (Link-Local Multicast Name Resolution) and NBT-NS (NetBIOS Name Service) are legacy name resolution protocols that attackers exploit to capture credentials through poisoning attacks. When a Windows client can’t resolve a hostname via DNS, it falls back to broadcasting LLMNR and NBT-NS queries across the network — and attackers respond with malicious answers, capturing authentication attempts. Tools like Responder and Inveigh make this attack trivial, turning misconfigured name resolution into domain compromise. This guide shows how to disable LLMNR and NBT-NS via Group Policy, with registry paths, PowerShell verification, testing procedures, and complete rollback instructions for Windows 11 and Server 2025 environments. ...

Platform SAS CTF 2026 Quals Difficulty Hard OS Network — Alpine Linux + FRR 10.0 Tags BGP sub-prefix hijack, FRR network-statement RIB origin, vtysh static routes, dnsmasq DNS sinkhole, OpenSSL self-signed certs, Python TLS termination + ALPN, RPKI/ROA defender perspective, IXP filtering Incident 67 from the SAS CTF 2026 Quals was the kind of network challenge that rewards patience. The category badge said “Network / BGP” and the brief read like an Internet routing exam: you’re a fresh hire at a small regional ISP, you’ve SSH’d into your edge router, and somewhere out on the public Internet there’s a crypto wallet gateway you’re not supposed to be able to touch. The router config is already half-built. The story all but tells you what to do. ...

SMBv1 should have died in 2017 when WannaCry ransomware exploited the EternalBlue vulnerability (MS17-010) to infect 300,000+ Windows systems worldwide in 72 hours. Yet five years later, most enterprise environments still have SMBv1 enabled by default — not because they need it, but because it’s legacy technical debt that “works” and nobody wants to break file shares. This guide shows how to disable SMBv1 on Windows Server safely: audit current usage, migrate dependencies to modern SMBv2/v3, remove the protocol entirely, and verify compliance across the fleet. ...