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Vulnerability of Java JRE: file access via XML entities

Synthesis of the vulnerability 

An attacker can provide XML data using an external entity, in order to access to the content of a file or to create a denial of service.
Impacted products: Java Oracle, RHEL.
Severity of this bulletin: 2/4.
Creation date: 01/02/2008.
Revision date: 04/02/2008.
Références of this threat: 231246, 6568262, BID-27553, CERTA-2008-AVI-216, CESA-2007-002, CVE-2008-0628, RHSA-2008:0245-01, VIGILANCE-VUL-7539.

Description of the vulnerability 

XML data can contain external entities (DTD):
  <!ENTITY name SYSTEM "file">
  <!ENTITY name SYSTEM "http://server/file">
To validate the XML document, the program can replace these entities by data coming from the file. When the program uses XML data coming from an untrusted source, this behavior leads to:
 - content disclosure from files of the server
 - private web site scan
 - a denial of service by opening a blocking file

To forbid this attack, this feature ("external general entities") is disabled in the JRE. However, a regression error, appeared in version 6, always enables this feature.

When a Java program handles XML data from a untrusted source, an attacker can therefore access to files or create a denial of service.
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This computer weakness announce impacts software or systems such as Java Oracle, RHEL.

Our Vigil@nce team determined that the severity of this security alert is medium.

The trust level is of type confirmed by the editor, with an origin of document.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this vulnerability.

Solutions for this threat 

Java JRE, JDK: version 6 Update 4.
Version 6 Update 4 is corrected:
  http://java.sun.com/javase/6/webnotes/ReleaseNotes.html#160_04
  http://java.sun.com/javase/downloads/index.jsp
For Solaris :
 - SPARC
    - 32 bit : 125136-05
    - 64 bit : 125137-05
 - x86
    - 32 bit : 125138-05
    - 64 bit : 125139-05

RHEL 5S: new java-1.6.0-bea packages.
New packages are available:
RHEL Desktop Supplementary version: java-1.6.0-bea-1.6.0.03-1jpp.2.el5
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