NVIDIA DGX BMC (AMI firmware): Default SNMP community strings on the DGX BMC

Impact

Default SNMP community strings on the DGX BMC. Anyone who can reach the BMC over SNMP enumerates hardware inventory, sensor data and configuration without authenticating - cheap reconnaissance that maps your fleet before a real attack. DGX-1 before 3.38.30, DGX-2 before 1.06.06.

Who can reach it

Anyone with UDP reach to the BMC's SNMP port on the management network.

What to do

Flash the DGX BMC firmware from NVIDIA's DGX firmware update container (DGX-1 to 3.38.30 or later, DGX-2 to 1.06.06 or later; DGX A100 per the bulletin's table). A BMC flash does not require the host OS to reboot but drops out-of-band management for several minutes and NVIDIA recommends a host power cycle afterwards, so treat it as a per-node maintenance window. Rotate every BMC and IPMI credential after the flash - flashing does not invalidate secrets an attacker already pulled. Keep BMCs on an isolated management VLAN with no route from tenant or job networks. Also change or disable SNMP community strings explicitly after flashing - a firmware update does not necessarily reset a configured default.

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