The program obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.
An attacker can supply a pointer for memory locations that the program is not expecting. If the pointer is dereferenced for a write operation, the attack might allow modification of critical program state variables, cause a crash, or execute code. If the dereferencing operation is for a read, then the attack might allow reading of sensitive data, cause a crash, or set a program variable to an unexpected value (since the value will be read from an unexpected memory location).
There are several variants of this weakness, including but not necessarily limited to:
The untrusted value is directly invoked as a function call.
In OS kernels or drivers where there is a boundary between "userland" and privileged memory spaces, an untrusted pointer might enter through an API or system call (see CWE-781 for one such example).
Inadvertently accepting the value from an untrusted control sphere when it did not have to be accepted as input at all. This might occur when the code was originally developed to be run by a single user in a non-networked environment, and the code is then ported to or otherwise exposed to a networked environment.
Many weaknesses related to pointer dereferences fall under the general
term of "memory corruption" or "memory safety." As of September 2010, there
is no commonly-used terminology that covers the lower-level variants.
Technical Impact: Read memory
If the untrusted pointer is used in a read operation, an attacker
might be able to read sensitive portions of memory.
Technical Impact: DoS: crash / exit /
If the untrusted pointer references a memory location that is not
accessible to the program, or points to a location that is "malformed"
or larger than expected by a read or write operation, the application
may terminate unexpectedly.
Technical Impact: Execute unauthorized code or
commands; Modify memory
If the untrusted pointer is used in a function call, or points to
unexpected data in a write operation, then code execution may be
labeled as a "type confusion" issue, also referred to as a "stale pointer." However, the bug ID says "contents are simply interpreted as a pointer... renderer ordinarily doesn't supply this pointer directly". The "handle" in the untrusted area is replaced in one function, but not another - thus also, effectively, exposure to wrong sphere (CWE-668).
Under-studied and probably under-reported as of September 2010. This
weakness has been reported in high-visibility software, but applied
vulnerability researchers have only been investigating it since
approximately 2008, and there are only a few public reports. Few reports
identify weaknesses at such a low level, which makes it more difficult to
find and study real-world code examples.
Mapped Taxonomy Name
Mapped Node Name
CERT C++ Secure Coding
Define and use a pointer validation
There are close relationships between incorrect pointer dereferences and
other weaknesses related to buffer operations. There may not be sufficient
community agreement regarding these relationships. Further study is needed
to determine when these relationships are chains, composites,
perspective/layering, or other types of relationships. As of September 2010,
most of the relationships are being captured as chains.