Re: VMware 1.1.2 Symlink Vulnerability

From: Oinos (oinosat_private)
Date: Mon Jan 24 2000 - 22:23:12 PST

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    The use of the /tmp directory is default in VMware, but configurable with
    the tmpDirectory = <directory> setting in the .cfg file for the guest
    operating system, or with the TMPDIR=<directory> setting in your shell
    environment.  This is documented on VMware's website.
    
    -Oinos
    
    -----Original Message-----
    From: Bugtraq List [mailto:BUGTRAQat_private]On Behalf Of harikiri
    Sent: Monday, January 24, 2000 8:49 AM
    To: BUGTRAQat_private
    Subject: VMware 1.1.2 Symlink Vulnerability
    
    w00w00 Security Advisory - http://www.w00w00.org/
    
    Title:          VMware 1.1.2 Symlink Vulnerability
    Platforms:      Linux Distributions with VMware 1.1.2 (build 364)
    Discovered:     17th January, 2000
    Local:          Yes.
    Remote:         No.
    Author:         harikiri <harikiriat_private>
    Vendor Status:  Notified.
    Last Updated:   N/A
    
    1. Overview
    
    VMware stores temporary log files within the /tmp directory. It does
    not check whether all of these files exist prior to creation, resulting
    in the potential for a symlink attack.
    
    
    2. Background
    
    VMware is a commercial application that enables the operation of "guest"
    operating systems within the host system. This is performed via the use of
    Virtual Machine technology.
    
    Due to the low-level requirements of VMware, it is necessary to run the
    program at a high privilege level, typically root.
    
    
    3. Issue
    
    VMware creates the file "/tmp/vmware-log" on startup. The existance and
    owner of the file is not checked prior to writing startup information to
    the file.
    
    NOTE: VMware uses other files in the /tmp directory. The one cited above
    is only a single example.
    
    
    4. Impact
    
    Local users may create a symlink from an arbitrary file to /tmp/vmware-log.
    When VMware is executed, the file pointed to by the symlink will be
    overwritten.
    
    This may be used as a local denial of service attack. There may also be a
    method to gain elevated privileges via the symlink attack, though none is
    known at this time.
    
    
    5. Recommendation
    
    Wait for a fix from the vendor.
    
    
    6. References
    
    - VMware Inc: http://www.vmware.com/
    - w00w00 Security Development: http://www.w00w00.org/
    
    EOF
    



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