Improper Enforcement of Behavioral Workflow

Incomplete Base
Structure: Simple
Description

The product supports a session in which more than one behavior must be performed by an actor, but it does not properly ensure that the actor performs the behaviors in the required sequence.

Extended Description

By performing actions in an unexpected order, or by omitting steps, an attacker could manipulate the business logic of the product or cause it to enter an invalid state. In some cases, this can also expose resultant weaknesses. For example, a file-sharing protocol might require that an actor perform separate steps to provide a username, then a password, before being able to transfer files. If the file-sharing server accepts a password command followed by a transfer command, without any username being provided, the product might still perform the transfer. Note that this is different than CWE-696, which focuses on when the product performs actions in the wrong sequence; this entry is closely related, but it is focused on ensuring that the actor performs actions in the correct sequence. Workflow-related behaviors include: - Steps are performed in the expected order. - Required steps are not omitted. - Steps are not interrupted. - Steps are performed in a timely fashion.

Common Consequences 1
Scope: Other

Impact: Alter Execution Logic

An attacker could cause the product to skip critical steps or perform them in the wrong order, bypassing its intended business logic. This can sometimes have security implications.

Demonstrative Examples 1
This code is part of an FTP server and deals with various commands that could be sent by a user. It is intended that a user must successfully login before performing any other action such as retrieving or listing files.

Code Example:

Bad
Python
python

user has requested a file*

python
python
The server correctly avoids sending files to a user that isn't logged in and doesn't own the file. However, the server will incorrectly list the files in any directory without confirming the command came from an authenticated user, and that the user is authorized to see the directory's contents.
Here is a fixed version of the above example:

Code Example:

Good
Python
python

...* if command == 'List_files': ``` if authenticated(user) and ownsDirectory(user,args): listFiles(args) return

python
Observed Examples 9
CVE-2011-0348Bypass of access/billing restrictions by sending traffic to an unrestricted destination before sending to a restricted destination.
CVE-2007-3012Attacker can access portions of a restricted page by canceling out of a dialog.
CVE-2009-5056Ticket-tracking system does not enforce a permission setting.
CVE-2004-2164Shopping cart does not close a database connection when user restores a previous order, leading to connection exhaustion.
CVE-2003-0777Chain: product does not properly handle dropped connections, leading to missing NULL terminator (Improper Null Termination) and segmentation fault.
CVE-2005-3327Chain: Authentication bypass by skipping the first startup step as required by the protocol.
CVE-2004-0829Chain: File server crashes when sent a "find next" request without an initial "find first."
CVE-2010-2620FTP server allows remote attackers to bypass authentication by sending (1) LIST, (2) RETR, (3) STOR, or other commands without performing the required login steps first.
CVE-2005-3296FTP server allows remote attackers to list arbitrary directories as root by running the LIST command before logging in.
References 8
Business Logic Flaws and Yahoo Games
Jeremiah Grossman
08-12-2006
ID: REF-795
Seven Business Logic Flaws That Put Your Website At Risk
Jeremiah Grossman
10-2007
ID: REF-796
Defying Logic: Theory, Design, and Implementation of Complex Systems for Testing Application Logic
Rafal Los and Prajakta Jagdale
2011
ID: REF-799
Real-Life Example of a 'Business Logic Defect' (Screen Shots!)
Rafal Los
2011
ID: REF-667
Toward Automated Detection of Logic Vulnerabilities in Web Applications
Viktoria Felmetsger, Ludovico Cavedon, Christopher Kruegel, and Giovanni Vigna
USENIX Security Symposium 2010
08-2010
ID: REF-801
Designing a Framework Method for Secure Business Application Logic Integrity in e-Commerce Systems
Faisal Nabi
International Journal of Network Security, Vol.12, No.1
2011
ID: REF-802
Modes of Introduction
Implementation
Taxonomy Mapping
  • WASC
Notes
Research Gap This weakness is typically associated with business logic flaws, except when it produces resultant weaknesses. The classification of business logic flaws has been under-studied, although exploitation of business flaws frequently happens in real-world systems, and many applied vulnerability researchers investigate them. The greatest focus is in web applications. There is debate within the community about whether these problems represent particularly new concepts, or if they are variations of well-known principles. Many business logic flaws appear to be oriented toward business processes, application flows, and sequences of behaviors, which are not as well-represented in CWE as weaknesses related to input validation, memory management, etc.