ConfD CLI Secure Shell Server Privilege Escalation Vulnerability
cisco-sa-confd-priv-esc-LsGtCRx4 · High · Published · Updated
A vulnerability in ConfD could allow an authenticated, local attacker to execute arbitrary commands at the level of the account under which ConfD is running, which is commonly root. To exploit this vulnerability, an attacker must have a valid account on the affected device. The vulnerability exists because the affected software incorrectly runs the SFTP user service at the privilege level of the account that was running when the ConfD built-in Secure Shell (SSH) server for CLI was enabled. If the ConfD built-in SSH server was not enabled, the device is not affected by this vulnerability. An attacker with low-level privileges could exploit this vulnerability by authenticating to an affected device and issuing a series of commands at the SFTP interface. A successful exploit could allow the attacker to elevate privileges to the level of the account under which ConfD is running, which is commonly root. Note: Any user who can authenticate to the built-in SSH server may exploit this vulnerability. By default, all ConfD users have this access if the server is enabled. Software updates that address this vulnerability have been released. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-confd-priv-esc-LsGtCRx4
Workarounds
There are no workarounds that address this vulnerability. However, a mitigation is available.
Administrators can disable the ConfD built-in SSH server and use an external SSH server such as OpenSSH. For guidance on disabling the built-in support of SSH in ConfD, see Section 4.1.1, “Disable built-in support for SSH in ConfD,” in the ConfD and High Security Applications V2 https://info.tail-f.com/hubfs/Whitepapers/Tail-f%20ConfDandHighSecurity%20rev%20F%202019-10-18.pdf application note.
While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.
| CVEs | CVE-2021-1572 |
|---|---|
| Cisco Bug IDs | CSCvy43896, CSCwh35199 |
| CVSS Score | Base 7.8 Base 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X |
| Product Names From Source | Cisco ConfD |
Related Products
| Product | CVE | Evidence |
|---|---|---|
| Cisco ConfD | CVE-2021-1572 | Cisco OpenVuln |