CWE-15: External Control of System or Configuration Setting
External Control of System or Configuration Setting
Weakness ID: 15 (Weakness Base)
Status: Incomplete
Description
Description Summary
One or more system settings or configuration elements can be externally controlled by a user.
Extended Description
Allowing external control of system settings can disrupt service or cause an application to behave in unexpected, and potentially malicious ways.
Time of Introduction
Implementation
Modes of Introduction
Setting manipulation vulnerabilities occur when an attacker can control
values that govern the behavior of the system, manage specific resources, or
in some way affect the functionality of the application.
Common Consequences
Scope
Effect
Other
Technical Impact: Varies by context
Demonstrative Examples
Example 1
The following C code accepts a number as one of its command line
parameters and sets it as the host ID of the current machine.
(Bad Code)
Example
Language: C
...
sethostid(argv[1]);
...
Although a process must be privileged to successfully invoke
sethostid(), unprivileged users may be able to invoke the program. The
code in this example allows user input to directly control the value of
a system setting. If an attacker provides a malicious value for host ID,
the attacker can misidentify the affected machine on the network or
cause other unintended behavior.
Example 2
The following Java code snippet reads a string from an
HttpServletRequest and sets it as the active catalog for a database
Connection.
(Bad Code)
Example
Language: Java
...
conn.setCatalog(request.getParameter("catalog"));
...
In this example, an attacker could cause an error by providing a
nonexistent catalog name or connect to an unauthorized portion of the
database.
Potential Mitigations
Phase: Architecture and Design
Strategy: Separation of Privilege
Compartmentalize the system to have "safe" areas where trust
boundaries can be unambiguously drawn. Do not allow sensitive data to go
outside of the trust boundary and always be careful when interfacing
with a compartment outside of the safe area.
Ensure that appropriate compartmentalization is built into the system
design and that the compartmentalization serves to allow for and further
reinforce privilege separation functionality. Architects and designers
should rely on the principle of least privilege to decide when it is
appropriate to use and to drop system privileges.
Phases: Implementation; Architecture and Design
Because setting manipulation covers a diverse set of functions, any
attempt at illustrating it will inevitably be incomplete. Rather than
searching for a tight-knit relationship between the functions addressed
in the setting manipulation category, take a step back and consider the
sorts of system values that an attacker should not be allowed to
control.
Phases: Implementation; Architecture and Design
In general, do not allow user-provided or otherwise untrusted data to
control sensitive values. The leverage that an attacker gains by
controlling these values is not always immediately obvious, but do not
underestimate the creativity of the attacker.
Description
