Multiple networking devices allow SNMP objects to be viewed/modified via ILMI community string

Overview

There is a vulnerability in the remote management architecture for Asynchronous Transfer Mode (ATM) networking devices that permits unauthorized access to configuration information. An attacker who gains access to an affected device can read and modify its configuration, creating a denial-of-service condition, an information leak, or both.

Description

Several networking products contain a default Simple Network Management Protocol (SNMP) community string that unintentionally grants read-write access to various SNMP objects. The vulnerability occurs in the implementation of the Integrated Local Management Interface (ILMI), an industry standard mechanism for remote management of ATM network interfaces. The ILMI allows the operator of an ATM device to obtain configuration information for the local node and any adjacent nodes. The interface is comprised of an ATM Interface MIB that is accessed using SNMP over the ATM protocol (as opposed to UDP). It is important to note that the ILMI specification requires that all SNMP communication between ILMI-compliant devices use a community string of “ILMI”, so it is not possible to simply change or disable that community string.

One instance of this vulnerability appears in several versions of the Cisco Internetworking Operating System (IOS). The exposed objects are located in three distinct Management Information Base (MIB) modules: the System group of MIB-II, the LAN-EMULATION-CLIENT (LANE) MIB, and the Private Network to Node Interface (PNNI) MIB. The first MIB is present in all SNMP devices and provides general system information, while the latter two are specific to ATM networking devices.

If implemented as intended, this community string is only accepted over an ATM ILMI interface, which prevents non-ATM traffic from accessing the objects available to the community. For vulnerable Cisco products, the ILMI community is not restricted to the ILMI interface, so it is possible to view and modify several objects residing in the System group of MIB-II, the LANE MIB, and the PNNI MIB via IP. Once access is obtained, an attacker can disrupt service on ATM networks and gather or modify system information, including system administrator contact information and details required for mapping the topology of a network.

It has been reported that this vulnerability also affects networking products from 3Com and Crosscomm/Olicom, which suggests that this problem may be common to several vendors’ products. For a list of affected vendors, please consult the Systems Affected section of this document.

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Impact

This vulnerability allows attackers to read and modify system information without proper authorization. Attackers exploiting this vulnerability may be able to re-route or disrupt traffic on ATM networks as well as gather information about network topology and system administration contacts.

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Solution

Apply a patch from your vendor

For a list of vendor-specific patch information, please consult the vendor section of this document.

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Vendor Information

976280

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3 Com __ Affected

Notified: August 29, 2001 Updated: September 28, 2001

Status

Affected

Vendor Statement

3Com exited the ATM market in March 2001 - as a result all 3Com ATM products are now obsolete.

Therefore, we have no intention at present to address the SNMP ILMI vulnerability issue for the products as reported in VU#976280.

For more information, please see the 3Com Commercial Product Obsolescence Policy at

http://www.3com.com/products/en_US/discontinued/policy.html

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23976280 Feedback>).

Cisco __ Affected

Notified: February 27, 2001 Updated: April 06, 2001

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Cisco has released an advisory that provides a list of affected products, along with instructions for obtaining fixed software. Because there are many possible combinations of hardware and software configurations, the CERT/CC recommends that all users of IOS software consult the following Cisco Security Advisory:

<http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml&gt;
It is important to note that the information leakage aspect of this vulnerability may affect any Cisco product whose IOS software includes ATM support, regardless of whether the product itself has the physical capability to include ATM interfaces. For further details, please consult the Cisco Security Advisory referenced above.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23976280 Feedback>).

Juniper Networks Not Affected

Notified: August 29, 2001 Updated: September 26, 2001

Status

Not Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23976280 Feedback>).

Crosscomm/Olicom Unknown

Updated: April 06, 2001

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23976280 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml&gt;
• <http://www.cisco.com/univercd/cc/td/doc/product/wanbu/8850r2/rel201/pnni/objects.htm&gt;
• <http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/ios113p/113tcavs.htm&gt;
• <http://www.securityfocus.com/bid/2427&gt;
• <http://www.protocols.com/pbook/ilmi.htm&gt;
• <http://www.atmdigest.com/pnni.htm&gt;
• <http://www.ncne.nlanr.net/news/workshop/vbns-techs2/Talks/mheld/&gt;
• <http://cell-relay.indiana.edu/cell-relay/FAQ/dictionary/I/ILMI.html&gt;
• <http://www-comm.itsi.disa.mil/atmf/pnni.html&gt;
• <ftp://ftp.atmforum.com/pub/approved-specs/af-ilmi-0065.000.pdf&gt;
• <ftp://ftp.atmforum.com/pub/approved-specs/&gt;

Acknowledgements

The CERT/CC thanks Cisco Systems for providing a description of this vulnerability and a patch to address it. We also thank Sean Donelan, Hank Nussbacher, and James A. T. Rice for their contributions.

This document was written by Jeffrey P. Lanza and is based on information obtained from a Cisco Security Advisory.

Other Information

CVE IDs:	CVE-2001-0380
Severity Metric:	54.68 Date Public: