Software Engineering Institute

EMC Legato NetWorker is a cross-platform backup and recovery application. It is also repackaged by Sun Microsystems as Solstice Backup and StorEdge Enterprise Backup, by FSC as Fujitsu Siemens Computers' NetWorker, by NEC as WebSAM NetWorker Powered by Legato, and by Fujitsu as NetWorker.

Legato PortMapper

The Legato PortMapper, also known as lgtomapper, is a service that listens on port 7938 and converts RPC program numbers into TCP or UDP protocol port numbers. The RPC pmap_set command can be used to map a remote procedure call to a port. pmap_unset destroys the mappings between a remote procedure call and a port.

The problem

With most portmapper implementations, the pmap_set and pmap_unset calls are restricted in ways such as only allowing connections from localhost. The Legato PortMapper allows any host to call pmap_set and pmap_unset. This may allow a remote, unauthenticated attacker to unregister existing NetWorker RPC services or register new RPC services.

A remote unauthenticated attacker may be able to create a denial-of-service condition by unregistering NetWorker services. An attacker may be able to eavesdrop on NetWorker process communications by registering a new RPC service.

Apply a patch or upgrade
Apply a patch or upgrade, as specified in the EMC Legato Technical Product Alert.

Sun Solstice Backup and StorEdge Enterprise Backup customers should see Sun Alert 101866 for patch availability.

Restrict Access

You may wish to block access to the vulnerable software from outside your network perimeter, specifically by blocking access to the ports used by NetWorker (typically TCP and UDP ports 7937-9936). This will limit your exposure to attacks. However, blocking at the network perimeter would still allow attackers within the perimeter of your network to exploit the vulnerability. The use of host-based firewalls in addition to network-based firewalls can help restrict access to specific hosts within the network. It is important to understand your network's configuration and service requirements before deciding what changes are appropriate.