Advisory ID: cisco-sa-20040219-ONS
For Public Release 2004 Februrary 19 17:00 UTC (GMT)
Multiple vulnerabilities exist in the Cisco ONS 15327 Edge Optical Transport Platform, the Cisco ONS 15454 Optical Transport Platform, the Cisco ONS 15454 SDH Multiplexer Platform, and the Cisco ONS 15600 Multiservice Switching Platform.
These vulnerabilities are documented as Cisco bug ID CSCec17308/CSCec19124(tftp), CSCec17406(port 1080), and CSCec66884/CSCec71157(SU access). There are workarounds available to mitigate the effects of these vulnerabilities.
This advisory is posted at
- Cisco ONS 15327 Edge Optical Transport Platform.
- Cisco ONS 15454 Optical Transport Platform.
- Cisco ONS 15454 SDH Multiplexer Platform.
- Cisco ONS 15600 Multiservice Switching Platform.
No other Cisco products are currently known to be affected by these vulnerabilities.
The affected Cisco ONS 15327, ONS 15454, ONS 15454 SDH, and ONS 15600 hardware is managed through the XTC, TCC+/TCC2, TCCi/TCC2, and TSC control cards respectively. These control cards are usually connected to a network isolated from the Internet and local to the customer's environment. This limits the exposure to the exploitation of the vulnerabilities from the Internet.
The TFTP service on UDP port 69 is enabled by default to allow both GET and PUT commands to be executed without any authentication. Using a TFTP client, it is possible to connect to the optical device and upload or retrieve ONS system files on the current active TCC in the /flash0 or /flash1 directories. It is not possible to upload or retrieve any user data files.
Cisco bug ID CSCec17308 documents the issue on the Cisco ONS 15327, ONS 15454 and ONS 15454 SDH, and Cisco bug ID CSCec19124 documents the issue on the Cisco ONS 15600 hardware.
- CSCec17406(port 1080)
The Cisco ONS 15327, ONS 15454 and ONS 15454 SDH hardware is susceptible to an ACK Denial of Service (DoS) attack on TCP port 1080. TCP port 1080 is used by network management applications to communicate with the controller card. The controller card on the optical device will reset under such an attack.
An ACK DoS attack is conducted by not sending the final ACK required for a 3-way TCP handshake to complete, and instead sending an invalid response to move the connection to an invalid TCP state.
The Cisco ONS 15600 Multiservice Switching Platform is not affected by this vulnerability.
- CSCec66884/CSCec71157(SU access)
Telnet access to the underlying VxWorks operating system, by default, is restricted to Superusers only. Due to this vulnerability, a superuser whose account is locked out, disabled, or suspended is still able to login (Telnet) into the VxWorks shell, using their previously configured password.
Cisco bug ID CSCec66884 documents the issue on the Cisco ONS 15327, ONS 15454 and ONS 15454 SDH, and Cisco bug ID CSCec71157 documents the issue on the Cisco ONS 15600 hardware.
The Internetworking Terms and Cisco Systems Acronyms online guides can be found at http://www.cisco.com/univercd/cc/td/doc/cisintwk/.
These vulnerabilities are documented in the Cisco Bug Toolkit ( registered customers only) as Cisco bug IDs CSCec17308/CSCec19124(tftp), CSCec17406(port 1080), and CSCec66884/CSCec71157(SU access). To access this tool, you must be a registered user and you must be logged in.
- CSCec17308/CSCec19124(tftp) -- This vulnerability could be exploited to launch a DoS attack on the optical device if corrupt ONS system files were to be uploaded to the controller card.
- CSCec17406(port 1080) -- This vulnerability could be exploited to launch a DoS attack on the optical device.
The timing for the data channels traversing the switch is provided by the control cards.
On the Cisco ONS 15454, ONS 15327, and ONS 15454 SDH hardware, whenever both the active and standby control cards are rebooting at the same time, the synchronous data channels traversing the switch drop traffic until the card reboots. Asynchronous data channels traversing the switch are not impacted. Manageability functions provided by the network element using the TCC+/TCC2, XTC, and TCCi/TCC2 control cards are not available until the control card reboots.
On the Cisco ONS 15600 hardware, whenever both the active and standby control cards are rebooting at the same time, there is no impact to the data channels traversing the switch because the TSC does a software reset which does not impact the timing being provided by the TSC for the data channels.
Manageability functions provided by the network element through the TSC control cards are not available until the control card reboots.
- CSCec66884/CSCec71157(SU access) -- This vulnerability could be exploited to gain unauthorized access to the optical device.
When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.
In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.
Upgrade procedures can be found as indicated below.
There are mitigation workarounds available for these vulnerabilities. The Cisco PSIRT recommends that affected users upgrade to a fixed software version of code.
Use access control lists on routers and firewalls that are installed in the network to allow only valid network management workstations to gain TFTP access to the XTC, TCC+/TCC2, TCCi/TCC2, or TSC control cards.
- CSCec17406(port 1080)
Use access control lists on routers and firewalls that are installed in the network to allow only valid network management workstations to gain TCP port 1080 access to the XTC, TCC+/TCC2, TCCi/TCC2, or TSC control cards.
- CSCec66884/CSCec71157(SU access)
Use access control lists on routers and firewalls that are installed in the network to allow only valid network management workstations to gain login (Telnet) access to the XTC, TCC+/TCC2, TCCi/TCC2, or TSC control cards.
Refer to http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml for examples on how to apply access control lists (ACLs) on Cisco routers.
Cisco has released free software updates that address these vulnerabilities. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.
Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at
, or as otherwise set forth at Cisco.com Downloads at
Do not contact firstname.lastname@example.org or email@example.com for software upgrades
Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at
Customers whose Cisco products are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.
The effectiveness of any workaround or fix is dependent on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.
Customers who purchase direct from Cisco but do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.
- +1 800 553 2447 (toll free from within North America)
- +1 408 526 7209 (toll call from anywhere in the world)
- e-mail: firstname.lastname@example.org
Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.
Refer to http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, and instructions and e-mail addresses for use in various languages.
The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
This vulnerability was reported to Cisco by internal testing.
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Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.
Initial public release.