cisco-sa-20170816-apic1 · High · Published · Updated
A vulnerability in Cisco Application Policy Infrastructure Controller (APIC) could allow an authenticated, remote attacker to gain higher privileges than the account is assigned. The attacker will be granted the privileges of the last user to log in, regardless of whether those privileges are higher or lower than what should have been granted. The attacker cannot gain root-level privileges. The vulnerability is due to a limitation with how Role-Based Access Control (RBAC) grants privileges to remotely authenticated users when login occurs via SSH directly to the local management interface of the APIC. An attacker could exploit this vulnerability by authenticating to the targeted device. The attacker's privilege level will be modified to match that of the last user to log in via SSH. An exploit could allow the attacker to gain elevated privileges and perform CLI commands that should be restricted by the attacker's configured role. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170816-apic1
There are workarounds that address this vulnerability. On the remote authentication server, each remote user can be configured with a Cisco Attribute-Value (AV) Pair, which includes a unique UNIX User Identifier. If this AV Pair is not present, then all users are assigned the same default UNIX User Identifier, which results in the vulnerability. For additional information on this configuration, please refer to Externally Managed Authentication Server Users Cisco AV Pair Format http://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/aci-fundamentals/b_ACI-Fundamentals/b_ACI-Fundamentals_chapter_01010.html#concept_78EBA92DE8D546F999226ABA6EBE3072 . Please contact the Cisco TAC if additional assistance is needed with this configuration.
In addition, while not workarounds, there are mitigations that can be used. This vulnerability only exists when SSH is used to connect to the local management interface of the APIC. If the connection uses the REST API or GUI interface, this vulnerability does not exist.