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Severity
High
Title
SIP Multimedia PC Client Unlimited Session DoS
Description

 

Nortel SIP Multimedia PC Client allows workers which are not deskbound to benefit from the same multimedia telephony experience regardless of their location.

 

Due to the client not implementing any limitation in the number of connections or active windows which can be spawned it is possible for an unauthenticated malicious user to exhaust resources on a given client by creating a very large number of sessions until the system can no longer handle the load leading to a Denial of Service (DoS) against the client system.

Details
Category
Denial of Service
Vendor
Nortel
Product
SIP Multimedia PC Client 4.x
Released
2008-06-25
updated
2008-06-25
Response
Attempting to address the issue
Recommendations

 

To completely address the issue requires a patch from Nortel. Currently no additional information is being provided by Nortel on the timing or availability of patches for the issue. Nortel customers with a valid support agreement may wish to speak with their support contact in order to obtain additional vendor details.

 

In the short term it is recommended that a VoIP aware IPS product, such as VoIPguard, with signatures to detect attempts to exploit this issue, be implemented to prevent it from being exploited. In addition, implementation of general best practice guidance such as controlling access to telephony networks via VLANs, access control lists, firewalls, network admission controls and/or other security devices will aid in limiting the exposure of this vulnerability.

 

Due to the client-centric nature of this issue centralized monitoring and protection for this issue may be difficult, therefore any monitoring that can be conducted within the switching infrastructure should also be attempted.

Tracking Id
VSRNT-2008-007
 

Each line represents an individual vulnerability or group of vulnerabilities. For example, "UCM Multiple Hardcoded Passwords" is presented here in a single line but was reported to Nortel as sixteen (16) individual vulnerabilities.

Severity Legend

Click on a level for description
Low

A low severity issue falls into one of two categories.  Firstly, there are those that are not directly exploitable and affect a single IP client, a small subset of the deployment, or are quite innocuous taken by themselves. In other words, they provide information which either involves only a small number (or single) client and that information requires considerable other information or effort to be useful to an attacker.  The other category of low severity issues includes those that are best practices which are not intended to directly mitigate an exploitable risk but to increase overall security robustness and demonstrate due diligence.

Medium

A medium severity issue is typically an issue which can lead to further exploitation or provides short-lived effect on a minimal number of clients.  It may not be immediately exploitable but provides sufficient information or access to move an attack closer to fruition.  Alternately it may provide unauthorized access not directly related to the VoIP portion of the network.

High

A high severity issue can be exploited to compromise one or more nodes within the deployment but may require authentication, especially when exploiting multiple systems simultaneously. In addition, it may be possible to protect against untrusted exploitation of the issue by deploying traditional security tools.

Critical

A critical severity issue can be exploited by an untrusted individual to compromise the entire deployment under review.  There are no security or protective mechanisms in place that will mediate exploitation of this vulnerability by an untrusted individual.

Vendor Response Legend

Patch available
Workaround proposed
Attempting to address the issue
No vendor response
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