Juniper Junos J-Web – Privilege Escalation Vulnerability

Sense of Security - Security Advisory - SOS-13-003 security advisory

Release Date.              10-Sep-2013
Last Update.               -              
Vendor Notification Date.  27-Sep-2012
Product.                   Juniper Junos J-Web 
Platform.                  Junos
Affected versions.         All builds prior to 2013-02-28 are affected
Severity Rating.           Medium
Impact.                    Privilege escalation
Attack Vector.             From remote with read-only authentication
Solution Status.           Vendor patch (not verified by SOS)
                           Disable J-Web or limit access
CVE reference.             CVE - not yet assigned

Details.
The J-Web is a GUI based network management application used on Junos 
devices. The web application is vulnerable to a remote code execution 
vulnerability which permits privilege escalation. The file/jsdm/ajax
/port.php allows execution of arbitrary user supplied PHP code via the
rs POST parameter. Code executes with UID=0 (root) privileges, however
you are confined to a chroot. Privilege escalation can be achieved by 
waiting for an administrator to log in and reading the contents of /tmp
to hijack their session.

Proof of Concept.
Code execution: Execute a command inside the Chroot: 
  POST /jsdm/ajax/port.php 
  rs=exec&rsargs[]=echo “hello” 

Privilege escalation: Read /tmp and hijack a session 
  POST /jsdm/ajax/port.php 
  rs=file_get_contents&rsargs[]=/tmp


Solution.
All Junos OS software releases built on or after 2013-02-28 have fixed
this specific issue. This fix has not been validated by SOS.
As a workaround disable J-Web, or limit access to only trusted hosts.
This issue is being tracked as PR 826518 and is visible on the Juniper
Customer Support website.


Discovered by.
Sense of Security Labs.


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