Public Vulnerability Reports

IBM Tivoli Provisioning Manager for OS Deployment TFTP Blocksize DoS Vulnerability



IBM Corp.'s Tivoli Provisioning Manager for OS Deployment is a network boot server that facilitates central management of networked workstations. It implements Preboot Execution Environment (PXE), a Web-based administration service, DHCP, TFTP, and several additional protocols. More information can be found at the following URL.


Remote exploitation of a denial of service vulnerability within version of IBM Corp.'s Tivoli Provisioning Manager for OS Deployment allows attackers to deny service to all product functionality.

This vulnerability specifically exists in the TFTP protocol implementation. When processing a read request (RRQ), an integer division by zero error can be triggered by supplying an invalid "blksize" argument. This exception is not handled and will result in the rembo.exe service terminating.


Exploitation allows an attacker to cause the service to terminate unexpectedly due to an exception that occurs when dividing by zero.

No authentication is required to access the vulnerable code. The attacker need only be able to send a specially crafted request to the TFTP port (UDP port 69) of the vulnerable machine.

This will deny service to all functionality provided by this service. This includes DHCP, TFTP, PXE, HTTP, HTTPS, as well as several other services.


iDefense has confirmed the existence of this vulnerability in version of IBM Corp.'s Tivoli Provisioning Manager for OS Deployment. Version was tested and found not to be vulnerable.


Employing firewalls to limit access to the affected service will mitigate exposure to this vulnerability.


The IBM Tivoli team has addressed this vulnerability within Tivoli Provisioning Manager for OS Deployment 5.1 Fix Pack 3. More information is available from IBM Document swg24016347 at the following URL.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-3268 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


06/19/2007 Initial vendor notification
06/19/2007 Initial vendor response
07/17/2007 Coordinated public disclosure


This vulnerability was reported to iDefense by Manuel Santamarina Suarez.

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Copyright © 2007 Verisign, Inc.

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