CWE-841

Class Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Incomplete MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Improper Enforcement of Behavioral Workflow

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.

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.

Consequences

Other — 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.

Detection

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)