DNS: Unassigned Opcode
This signature detects DNS requests that use an unassigned opcode. No RFC currently has a use defined for these opcodes, therefore, their use is anomalous. Many Trojan BotNets use a pseudo-DNS format for command and control, which can trigger this signature
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3