Software Engineering Institute

CWE-347: Improper Verification of Cryptographic Signature

IOActive reports that Cobham's thraneLINK protocol does not verify cryptographic signatures for firmware updates before installing them. A remote unauthenticated attacker may use the SLPFindSrvs protocol function to discover thraneLINK devices on the network then send a crafted SNMP request to have the device download a firmware update from a TFTP server under the control of the attacker.

The vendor Cobham has provided the following statement:
Cobham SATCOM has found that potential exploitation of the vulnerabilities presented requires either physical access to the equipment or connectivity to the maintenance part of the network, which also requires a physical presence at the terminal.

Specifically, in the aeronautical and maritime world, there are very strict requirements for equipment installation and physical access to the equipment is restricted to authorized personnel.

All Cobham network devices are part of a network with a very specific network topology. Equipment and network devices are segregated into clear network segments with different access levels.

Maintenance of Cobham network devices is usually carried out by equipment that is physically connected to the network device itself (maintenance port) or connected to an Ethernet switch within a protected network segment. From a network security perspective, Cobham devices can therefore only be subject to attacks if the attacker has either physical access to the device or segment or the network has been installed incorrectly.

Cobham SATCOM will continue to evaluate any potential vulnerabilities with its equipment and implement increased security measures if required.

A remote unauthenticated attacker may be able to deploy a malicious firmware image to a thraneLINK device and execute arbitrary code.

We are currently unaware of a practical solution to this problem. Please consider the following workaround.

Restrict Access

Enable firewall rules that restrict TFTP access to only trusted sources for thraneLINK devices. To stop an attacker from discovering thraneLINK devices, block broadcast requests for UDP port 427 to thraneLINK devices from untrusted sources.