External Control of System or Configuration Setting

Description

Allowing external control of system settings can disrupt service or cause an application to behave in unexpected, and potentially malicious ways.

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

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.

...
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 Two

The following Java code snippet reads a string from an HttpServletRequest and sets it as the active catalog for a database Connection.

...
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.

See Also