[ISN] Flaws in Microsoft VM. Fix now

From: InfoSec News (isnat_private)
Date: Thu Sep 19 2002 - 23:52:16 PDT

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    By John Leyden
    Posted: 19/09/2002 at 16:31 GMT
    Microsoft has alerted the world+dog to a trio of vulns in its
    implementation of Java Virtual Machine. The most serious enables an
    attacker to gain "complete control" over a victim's system. So get
    patching now.
    In an advisory [1], the company warns that the flaws to Microsoft VM,
    which ships as part of most versions of Windows and IE, are a critical
    risk to users.
    First, there's a flaw in a class which supports the use of XML by Java
    applications. This is supposed to differentiate between trusted and
    untrusted applets - except it doesn't, allowing any old applet to take
    "virtually any desired action on a user's system".
    The second vulnerability involves Java Database Connectivity (JDBC)  
    classes which enable Java applications to connect to and use data from
    a wide variety of sources. The vulnerability results because of a flaw
    in the way the classes vet a request to load and execute a DLL on a
    user's system.
    However, it's possible to spoof this check with a malformed request,
    which allows crackers to load and execute any old DLL on a victim's
    system, with potentially unpleasant consequences.
    The last flaw also involves JDBC classes, and results because "certain
    functions in the classes don't correctly validate handles that are
    provided as input", MS explains.
    One straightforward use of this flaw, Redmond helpfully explains,
    would be to supply invalid data instead of an actual handle when
    calling such a function; this would cause IE to fail.
    The exploit scenarios for unprotected users are all too familiar.
    An attacker would either create a web page which, when opened,
    exploits the desired vulnerability, or construct a
    maliciously-formated HTML mail.
    Setting up email clients to open HTML emails in Restricted Sites Zone
    guards against the risk; or admins could filter out mobile code
    entirely, MS suggests.
    [1] http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS02-052.asp
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