Symptom
A vulnerability in the CLI implementation of a specific command used for image maintenance for Cisco NX-OS Software could allow an authenticated, local attacker to overwrite any file on the file system including system files. These file overwrites by the attacker are accomplished at the root privilege level.
The vulnerability occurs because there is no verification of user-input parameters and or digital-signature verification for image files when using a specific CLI command. An attacker could exploit this vulnerability by authenticating to the device and issuing a command at the CLI. Because an exploit could allow the attacker to overwrite any file on the disk, including system files, a denial of service (DoS) condition could occur. The attacker must have valid administrator credentials for the affected device to exploit this vulnerability.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-nxos-file-write
Conditions
Please refer to the Security Advisory.
Workaround
Please refer to the Security Advisory.
Further Problem Description
Please refer to the Security Advisory.
PSIRT Evaluation
The Cisco PSIRT has assigned this bug the following CVSS version 3 score. The Base CVSS score as of the time of evaluation is 6.7:
https://tools.cisco.com/security/center/cvssCalculator.x?version=3.0&vector=CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CVE ID CVE-2019-1729 has been assigned to document this issue.
Additional information on Cisco''s security vulnerability policy can be found at the following URL:
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html
