Summary
Affected Products
Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: FINAL
Distribution
Revision History
Cisco Security Procedures
Security Scanning software can cause a memory error in Cisco IOS® Software that will cause a reload to occur. This vulnerability affects only Cisco IOS software version 12.1(2)T and 12.1(3)T, and limited deployment releases based on those versions.
Customers using the affected Cisco IOS software releases are urged to upgrade as soon as possible to later versions that are not vulnerable to this defect. Vulnerable products and releases are listed in detail below.
The security scanner makes TCP connection attempts to various ports, looking for open ports to further investigate known vulnerabilities with those services associated with certain ports. However, a side effect of the tests exposes the defect described in this security advisory, and the router will reload unexpectedly as soon as it receives a request to review or write the configuration file.
This defect is documented as Cisco Bug ID CSCds07326.
The complete notice will be available at http://www.cisco.com/warp/public/707/cisco-sa-20010524-ios-tcp-scanner-reload.shtml.
This section provides details on affected products.
It is impossible to list all Cisco products in this notice; the lists below include only the most commonly used or most asked-about products.
If you are unsure whether your device is running Cisco IOS software, log into the device and issue the command show version. Cisco IOS software will identify itself simply as "IOS" or "Internetwork Operating System Software". Other Cisco devices either will not have the show version command, or will give different output.
Cisco devices that run Cisco IOS software include the following:
The affected software versions are relatively new, and are not necessarily available on every device listed above.
If you are not running Cisco IOS software, you are not affected by this vulnerability. Cisco devices which do not run Cisco IOS software, and are not affected by this vulnerability, include the following:
No other Cisco products are currently known to be affected by these vulnerabilities.
An attempt to make a TCP connection to ports 3100-3999, 5100-5999, 7100-7999, and 10100-10999 will cause the router to unexpectedly reload at the next show running-config, or write memory, or any command that causes the configuration file to be accessed. Cisco IOS software cannot be configured to support any services that might listen at those port addresses, and cannot be configured to accept connections on those ports, however, connection attempts to these ports in the affected version will cause memory corruption, later leading to an unexpected reload.
Software packages are available from various commercial and free sites that perform automated remote tests for computer security vulnerabilities by scanning computers on a network for known security flaws. A common log message in environments that experienced security scan related crashes was the "attempt to connect to RSHELL" error message.
The described defect can be used to mount a denial of service (DoS) attack on any vulnerable Cisco product, which may result in violations of the availability aspects of a customer's security policy. This defect by itself does not cause the disclosure of confidential information nor allow unauthorized access.
This defect was introduced in version 12.1(1.3)T, and is repaired in the following versions which are based on the 12.1(2)T and 12.1(3)T releases.
The following table summarizes the Cisco IOS software releases that are known to be affected, and the earliest estimated dates of availability for the recommended fixed versions. Dates are always tentative and subject to change.
Each row of the table describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix and the anticipated date of availability for each are listed in the "Rebuild", "Interim", and "Maintenance" columns. A device running any release in the given train that is earlier than the release in a specific column (less than the earliest fixed release) is known to be vulnerable, and it should be upgraded at least to the indicated release or a later version (greater than the earliest fixed release label).
When selecting a release, keep in mind the following definitions:
In the table below, the logical superseding software is recommended when there is no rebuild or maintenance planned for a specific software release. Customers should verify that planned upgrades will meet their requirements. For further details, see the IOS Release Notes for each Cisco IOS Train. http://www.cisco.com/univercd/cc/td/doc/product/software/index.htm. 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 TAC for assistance as shown later in this notice.
More information on Cisco IOS Software release names and abbreviations is available at http://www.cisco.com/en/US/products/sw/iosswrel/tsd_products_support_category_home.html.
|
Major Release |
Description or Platform |
Availability of Repaired Releases* |
||
|---|---|---|---|---|
|
Unaffected Earlier Releases |
Rebuild |
Interim** |
Maintenance |
|
|
12.0 and earlier, all variants |
Numerous |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
12.1 |
General Deployment (GD) candidate: all platforms |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1AA |
Dial Support |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1CX |
Core/ISP support: GSR, RSP, C7200 |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1DA |
xDSL Support: 6100, 6200 |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1DB |
Cisco 6400 Universal Access Concentrator |
12.1(4)DB |
||
|
12.1DC |
xDSL NRP support: c6400r |
12.1(4)DC |
||
|
12.1E |
Core/ISP Support: GSR, RSP, c7200 |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1EC |
Early Deployment (ED): ubr7200, UBR Headend platforms |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1EX |
Catalyst 6000 |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1EY |
Catalyst 8510, 8540, LS1010 |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1T |
New technology Early Deployment (ED): all platforms |
12.1(4.3)T |
12.1(5)T |
|
|
12.1XA |
Early Deployment (ED): limited platforms |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1XB |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XC |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XD |
Early Deployment (ED): limited platforms |
Not vulnerable |
Not vulnerable |
Not vulnerable |
|
12.1XE |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XF |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XG |
Early Deployment (ED): limited platforms |
12.2T*** |
||
|
12.1XH |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XI |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XJ |
Early Deployment (ED): limited platforms |
12.2T*** |
||
|
12.1XK |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XL |
Early Deployment (ED): limited platforms |
12.2(1) |
||
|
12.1XM |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XP |
Early Deployment (ED): limited platforms |
12.2T*** |
||
|
12.1XQ |
Early Deployment (ED): limited platforms |
12.2T*** |
||
|
12.1XR |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XS |
Early Deployment (ED): limited platforms |
12.1(5)XS |
||
|
12.1XT |
Early Deployment (ED): limited platforms |
12.2T*** |
||
|
12.1XU |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XV |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XW |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XX |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XY |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1XZ |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1YA |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1YB |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1YC |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
12.1YD |
Early Deployment (ED): limited platforms |
Not Vulnerable |
Not Vulnerable |
Not Vulnerable |
|
Notes |
||||
|
* All dates are estimated and subject to change. ** Interim releases are subjected to less rigorous testing than regular maintenance releases, and may have serious bugs. *** This release does not have a rebuild solution. Customers should upgrade to 12.2T when it becomes available. This is not a misprint. |
||||
This vulnerability can be mitigated by configuring access lists and applying access groups on all interfaces or on external devices or firewalls to prevent connection attempts to affected routers, and to eliminate router addresses in any planned security scanning exercises.
Cisco has made free software available to address this vulnerability for affected customers. 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 http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "psirt@cisco.com" or "security-alert@cisco.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 http://www.cisco.com.
Customers whose Cisco products are provided or maintained through prior or existing agreement 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 who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.
Have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.
Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special 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 vulnerabilities described in this advisory. However, many reports of reloads related to this vulnerability have been reported by customers, due to customer use of security scanning software.
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This notice will be posted on Cisco's Worldwide Web site at http://www.cisco.com/warp/public/707/cisco-sa-20010524-ios-tcp-scanner-reload.shtml. In addition to Worldwide Web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients:
Future updates of this advisory, if any, will be placed on Cisco's Worldwide Web site, 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.
|
Revision 1.1 |
2001-May-24 |
Made changes to the workarounds section |
|
Revision 1.0 |
2001-May-24 |
Initial public release. |
Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's Worldwide Web site at http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices.
All contents are Copyright © 2006-2007 Cisco Systems, Inc. All rights reserved. Important Notices and Privacy Statement.
| Updated: May 24, 2001 | Document ID: 13632 |