A backdoor ended up fixed in Flex System, RackSwitch and BladeCenter switches from Lenovo and IBM.
The flaw, tracked as CVE-2017-3765, affects the Enterprise Network Operating System (ENOS) running on affected devices.
“An authentication bypass mechanism known as ‘HP Backdoor’ was discovered during a Lenovo security audit in the Telnet and Serial Console management interfaces, as well as the SSH and Web management interfaces under certain limited and unlikely conditions,” Lenovo said in a security advisory.
“An attacker could gain access to the switch management interface, permitting settings changes that could result in exposing traffic passing through the switch, subtle malfunctions in the attached infrastructure, and partial or complete denial of service,” Lenovo said.
“This bypass mechanism can be accessed when performing local authentication under specific circumstances using credentials that are unique to each switch. If exploited, admin-level access to the switch is granted,” the company said of the high severity vulnerability.
ENOS is the operating system that powers Lenovo’s RackSwitch and Flex System embedded switches. ENOS was initially developed by Nortel’s Blade Server Switch Business Unit, which spun off in 2006 to become BLADE Network Technologies (BNT). IBM acquired BNT in 2010 and in 2014 sold it to Lenovo.
The problematic feature, introduced by Nortel in 2004 at the request of a customer, can be found in Lenovo devices and IBM Flex System, BladeCenter and RackSwitch switches that still use the ENOS firmware.
Lenovo patched the security hole with the release of ENOS 220.127.116.11 and also provided workarounds.