[NEWS] JavaMail Directory Traversal Vulnerability

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  JavaMail Directory Traversal Vulnerability
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SUMMARY

The JavaMail API provides a platform-independent and protocol-independent 
framework to build mail and messaging applications. The JavaMail API is 
implemented as a Java platform optional package and is also available as 
part of the Java 2 platform, Enterprise Edition.

The JavaMail API doesn't properly validate filename attribute in 
Content-Disposition header, making it vulnerable to directory traversal 
attacks. Successful exploitation of this vulnerability allows writing 
arbitrary content in any directory accessible to the servlet running 
JavaMail.

DETAILS

Vulnerable Systems:
 * JavaMail version 1.3.2

MimeBodyPart.getFileName () method in the JavaMail API get the filename 
associated with body part, if possible. The body part represents an 
"attachment" that was loaded from a file. While in the documentation of 
the function claims that the file name does not need to include path of 
directory, it doesn't properly filter file name attribute in 
Content-Disposition header, and it is possible to place a directory path 
with the file name.

In order to exploit the problem, send an email with the following filename 
attribute in Content-Disposition header:
./../../file.ext

This will write attachment three directories backward from expected 
location, as long as the servlet processing the email has writable access 
to that directory.

Example:
This method uses getFileName () method to save the first attachment into a 
file:

protected void saveMailAttachment (javax.mail.internet.MimeMultipart mp) {
 try {
   int n = mp.getCount();
   javax.mail.Part p = mp.getBodyPart (0);
   String disposition = p.getDisposition ();
 
   if (disposition != null && (disposition.equalsIgnoreCase 
(javax.mail.Part.ATTACHMENT) || disposition.equalsIgnoreCase 
(javax.mail.Part.INLINE) ) ) {
      String filename = p.getFileName ();
      File f = new File (filename);
      OutputStream os = new BufferedOutputStream (new FileOutputStream (f) 
);
      InputStream is = p.getInputStream ();
      int c;
      while ( (c = is.read () ) != -1) os.write (c);
      os.close ();
   }
 } catch (Exception e) { }
}


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> Rafael San 
Miguel Carrasco .



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