IBM Tivoli Provisioning Manager for OS Deployment TFTP Blocksize DoS Vulnerability iDefense Security Advisory 07.17.07 http://labs.idefense.com/intelligence/vulnerabilities/ Jul 17, 2007 I. BACKGROUND 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. http://www-306.ibm.com/software/tivoli/products/prov-mgr-os-deploy/ II. DESCRIPTION Remote exploitation of a denial of service vulnerability within version 18.104.22.168 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. III. ANALYSIS 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. IV. DETECTION iDefense has confirmed the existence of this vulnerability in version 22.214.171.124 of IBM Corp.'s Tivoli Provisioning Manager for OS Deployment. Version 126.96.36.199 was tested and found not to be vulnerable. V. WORKAROUND Employing firewalls to limit access to the affected service will mitigate exposure to this vulnerability. VI. VENDOR RESPONSE 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. http://www-1.ibm.com/support/docview.wss?uid=swg24016347 VII. CVE INFORMATION 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 (http://cve.mitre.org/), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 06/19/2007 Initial vendor notification 06/19/2007 Initial vendor response 07/17/2007 Coordinated public disclosure IX. CREDIT This vulnerability was reported to iDefense by Manuel Santamarina Suarez. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2007 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customerservice@private for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
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