-- Corsaire Security Advisory -- Title: VMware ESX Server Cross Site Scripting issue Date: 14.11.05 Application: VMware ESX prior to 2.5.2 upgrade patch 2 VMware ESX prior to 2.1.2 upgrade patch 6 VMware ESX prior to 2.0.1 upgrade patch 6 Environment: VMware ESX Author: Stephen de Vries [stephen.de.vries@corsaire.com] Audience: General distribution Reference: c051114-002 -- Scope -- The aim of this document is to clearly define an issue that exists with the VMware ESX Server product [1] that will allow a remote attacker to inject arbitrary active scripting content, such as JavaScript, into a web session. -- History -- Discovered: 11.11.05 (Stephen de Vries) Vendor notified via client: 15.11.05 Vendor notified directly: 19.05.06 Document released: 01.06.06 -- Overview -- VMware ESX Server is described [1] as virtual infrastructure software for partitioning, consolidating and managing servers in mission-critical environments. The software provides a virtualization layer that allows multiple x86 based operating systems to run on the same hardware concurrently. The ESX Server product differs from other VMware products in that it does not require a "host" operating system to be provided by the user. Instead, it uses a custom x86 kernel as the host, along with a customised Linux operating system as a "console O/S". VMware ESX Server includes a number of network services and a web application, called the "VMware Management Interface" that can be used to perform remote administration of the system. -- Analysis -- The VMware ESX Server product provides a web application to perform management of the system. One of the functions of this application is to allow administrative users to view log files, such as syslog, through a browser. No encoding of syslog data is performed to ensure that HTML meta-characters are not interpreted by the browser. This allows an attacker to inject HTML content, including JavaScript, into the syslog file where it would be rendered or executed when viewed through the Management Interface. Since the raw syslog data is displayed between
tags, it is necessary to close the tag for a clean injection. Two injection methods were detected: 1. An attacker could simply attempt to log in to the Management Interface with a username that contains the injection script, such as:
2. An attacker could attempt to log in to the ftp server with a username containing a similar injection string. It should be noted that the ftp server is not enabled by default, however, the Management Interface is. This flaw could be used to conduct any number of Cross Site Scripting attacks [2], such as Session Hijacking, Cross Site Request Forgery or apparent falsification of the syslog data. The risk of this vulnerability is increased due to the fact that only administrative users have permission to view the syslog files through the Management Interface. Should a Session Hijacking attack be successful, it would therefore likely yield administrative access. -- Recommendations -- Upgrade to a version of the VMware ESX product that does not exhibit this issue: VMware ESX 2.5.2 upgrade patch 2 and later VMware ESX 2.1.2 upgrade patch 6 and later VMware ESX 2.0.1 upgrade patch 6 and later -- CVE -- The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2005-3619 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardises names for security problems. -- References -- [1] http://www.vmware.com/products/esx/ [2] http://www.aspectsecurity.com/topten/xss.html -- Revision -- a. Initial release. b. Minor edits. c. Released. -- Distribution -- The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Corsaire accepts no responsibility for any damage caused by the use or misuse of this information. -- Disclaimer -- The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Corsaire accepts no responsibility for any damage caused by the use or misuse of this information. -- About Corsaire -- Corsaire are a leading information security consultancy, founded in 1997 in Guildford, Surrey, UK. Corsaire bring innovation, integrity and analytical rigour to every job, which means fast and dramatic security performance improvements. Our services centre on the delivery of information security planning, assessment, implementation, management and vulnerability research. A free guide to selecting a security assessment supplier is available at http://www.penetration-testing.com Copyright 2005-2006 Corsaire Limited. All rights reserved.