Security advisory for LedgerSMB 1.2.0-1.2.6

["Chris Travers" <..hidden..>]

This is the advisory concerning the security hole that was patched in 1.2.7.


A security issue has been found which allows an unauthenticated user
to bypass the authentication system in LedgerSMB 1.2.0 through 1.2.6.

Severity:  Highly Critical
Versions affected:  1.2.0 through 1.2.6
Status: Vendor solution available (upgrade to 1.2.7)
Effect: Authentication bypass.
Required knowledge:  A valid username for any user.

This is listed as highly critical because it could be used to access
the entire application masquerading as a different user than one is
authorized to use.  This is a serious risk in any financial system as
it could be a vector for embezzlement and covering up dishonest
activities.

Origins and Information:
The problem occurs because of a flaw in the redirect code which was
replaced in order to support additional environments.  The redirection
code in this case can be accessed through the login module and tricked
into providing access without proper authentication.

Exploits can be performed by setting the action variable in the http
request to "redirect" with a callback variable set to the escaped URL
representing the desired action.

Not affected:
LedgerSMB prior to 1.2.0 or after 1.2.6
SQL-Ledger (any version)

Solution:
Upgrade to LedgerSMB 1.2.7

Credit:
This was discovered by a core member of the LedgerSMB team who has
asked to remain anonymous.  This disclosure is intended to help those
who manufacture security products or are responsible for the security
of their networks.  All questions regarding more information on this
vulnerability can be directed to Chris Travers (
..hidden.. or ..hidden..).

Best Wishes,
Chris Travers