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AUSCERT External Security Bulletin Redistribution
Cisco Network Convergence System 1000 Series TFTP Directory
21 February 2019
AusCERT Security Bulletin Summary
Product: Cisco Network Convergence System 1000 Series
Cisco IOS XR Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Access Confidential Data -- Remote/Unauthenticated
CVE Names: CVE-2019-1681
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Cisco Network Convergence System 1000 Series TFTP Directory Traversal
Advisory ID: cisco-sa-20190220-ncs
FirstÂ Published: 2019Â FebruaryÂ 20Â 16:00Â GMT
VersionÂ 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvk32415
A vulnerability in the TFTP service of Cisco Network Convergence System
1000 Series software could allow an unauthenticated, remote attacker to
retrieve arbitrary files from the targeted device, possibly resulting in
The vulnerability is due to improper validation of user-supplied input
within TFTP requests processed by the affected software. An attacker could
exploit this vulnerability by using directory traversal techniques in
malicious requests sent to the TFTP service on a targeted device. An
exploit could allow the attacker to retrieve arbitrary files from the
targeted device, resulting in the disclosure of sensitive information.
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:
o Vulnerable Products
This vulnerability affects Cisco IOS XR Software releases prior to Release
6.5.2 for Cisco Network Convergence System 1000 Series devices when the
TFTP service is enabled.
Determining the Cisco IOS XR Software Release
To determine which Cisco IOS XR Software release is running on a device
and the name of the device on which it is running, administrators can log
in to the device and use the show version command in the CLI. If the
device is running Cisco IOS XR Software, Cisco IOS XR Software or similar
text appears in the system banner. The name of the hardware product
appears on the line after the location of the system image file.
The following example shows the output of the show version command on a
Cisco NCS-1001 Network Convergence System 1001 device that is running
Cisco IOS XR Software Release 6.5.2:
Cisco IOS XR Software, Version 18.104.22.168I Copyright (c) 2013-2018 by Cisco Systems, Inc.
Built By : deenayak
Built On : Sat Jan 26 23:45:04 PST 2019
Built Host : iox-ucs-023
Workspace : /auto/iox-ucs-023-san2/prod/22.214.171.124I.SIT_IMAGE/ncs1001/ws
Version : 126.96.36.199I
Location : /opt/cisco/XR/packages/
cisco NCS-1001 () processor
System uptime is 2 days 14 hours 54 minutes
Customers can run the following command to determine if the TFTP service
is enabled and running on a Cisco Network Convergence System 1000 Series
device. The device is not vulnerable if the TFTP service is not enabled,
and the service is not enabled in default configurations.
show processes all | in tftpd
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability. Other Cisco Network
Convergence System series devices are not affected by this vulnerability.
o There are no workarounds that address this vulnerability.
o Cisco has released free software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
Additionally, customers may only download software for which they have a
valid license, procured from Cisco directly, or through a Cisco authorized
reseller or partner. In most cases this will be a maintenance upgrade to
software that was previously purchased. Free security software updates do
not entitle customers to a new software license, additional software
feature sets, or major revision upgrades.
When considering software upgrades, customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts page, to determine exposure and a
complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the
Cisco Technical Assistance Center (TAC) or their contracted maintenance
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service
contract and customers who make purchases through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale
should obtain upgrades by contacting the Cisco TAC:
Customers should have the product serial number available and be prepared
to provide the URL of this advisory as evidence of entitlement to a free
Cisco fixed this vulnerability in Cisco IOS XR Software Release 6.5.2 for
Cisco Network Convergence System 1000 Series devices.
Customers can download the software from the Software Center on Cisco.com
by doing the following:
1. Click Browse all
2. Navigate to Optical Networking > Optical Data Center Interconnects >
Network Convergence System 1000 Series > Network Convergence System
1001 or Network Convergence System 1002 > IOS XR Software
3. Access releases by using the left pane of the Network Convergence
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
o This vulnerability was found during internal security testing.
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy. This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
Subscribe to Cisco Security Notifications
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | -- | Final | 2019-February-20 |
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