CWE-841: Improper Enforcement of Behavioral Workflow
Weakness ID: 841
Abstraction: Base Structure: Simple
Status: Incomplete
Presentation Filter:
Description
The software 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 software 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 software might still perform the transfer.
Note that this is different than CWE-696, which focuses on when the software 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.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (CWE-1000)
Nature
Type
ID
Name
ChildOf
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.
The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase
Note
Implementation
REALIZATION: This weakness is caused during implementation of an architectural security tactic.
Common Consequences
The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope
Impact
Likelihood
Other
Technical Impact: Alter Execution Logic
An attacker could cause the software to skip critical steps or perform them in the wrong order, bypassing its intended business logic. This can sometimes have security implications.
Demonstrative Examples
Example 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.
(bad code)
Example Language: Python
def dispatchCommand(command, user, args):
if command == 'Login':
loginUser(args) return
# user has requested a file if command == 'Retrieve_file':
if authenticated(user) and ownsFile(user,args): sendFile(args) return
if command == 'List_files':
listFiles(args) return
...
The server correctly does not send files to a user that isn't logged in and doesnt 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:
(good code)
Example Language: Python
def dispatchCommand(command, user, args):
... if command == 'List_files':
if authenticated(user) and ownsDirectory(user,args):
FTP 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.
FTP server allows remote attackers to list arbitrary directories as root by running the LIST command before logging in.
Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).
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.
[REF-801] Viktoria Felmetsger, Ludovico Cavedon, Christopher Kruegel
and Giovanni Vigna. "Toward Automated Detection of Logic Vulnerabilities in Web Applications". USENIX Security Symposium 2010. 2010-08.
<http://www.usenix.org/events/sec10/tech/full_papers/Felmetsger.pdf>.
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March 29, 2018
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Description
Relevant to the view "Research Concepts" (CWE-1000)
