The product uses a fixed or controlled search path to find resources, but one or more locations in that path can be under the control of unintended actors.
Extended Description
Although this weakness can occur with any type of resource, it is frequently introduced when a product uses a directory search path to find executables or code libraries, but the path contains a directory that can be modified by an attacker, such as "/tmp" or the current working directory.
In Windows-based systems, when the LoadLibrary or LoadLibraryEx function is called with a DLL name that does not contain a fully qualified path, the function follows a search order that includes two path elements that might be uncontrolled:
the directory from which the program has been loaded
the current working directory.
In some cases, the attack can be conducted remotely, such as when SMB or WebDAV network shares are used.
In some Unix-based systems, a PATH might be created that contains an empty element, e.g. by splicing an empty variable into the PATH. This empty element can be interpreted as equivalent to the current working directory, which might be an untrusted search element.
Alternate Terms
DLL preloading:
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.
Binary planting:
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.
Insecure library loading:
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.
Time of Introduction
Implementation
Applicable Platforms
Languages
Language-independent
Operating Systems
OS-independent
Common Consequences
Scope
Effect
Confidentiality
Integrity
Availability
Technical Impact: Execute unauthorized code or
commands
Product searches /tmp for modules before other
paths.
Potential Mitigations
Phase: Implementation
Strategy: Input Validation
Assume all input is malicious. Use an "accept known good" input
validation strategy, i.e., use a whitelist of acceptable inputs that
strictly conform to specifications. Reject any input that does not
strictly conform to specifications, or transform it into something that
does.
When performing input validation, consider all potentially relevant
properties, including length, type of input, the full range of
acceptable values, missing or extra inputs, syntax, consistency across
related fields, and conformance to business rules. As an example of
business rule logic, "boat" may be syntactically valid because it only
contains alphanumeric characters, but it is not valid if the input is
only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs
(i.e., do not rely on a blacklist). A blacklist is likely to miss at
least one undesirable input, especially if the code's environment
changes. This can give attackers enough room to bypass the intended
validation. However, blacklists can be useful for detecting potential
attacks or determining which inputs are so malformed that they should be
rejected outright.
Phase: Implementation
Strategy: Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass whitelist validation schemes by introducing dangerous inputs after they have been checked.
Unlike untrusted search path (CWE-426), which inherently involves control over the definition of a control sphere (i.e., modification of a search path), this entry concerns a fixed control sphere in which some part of the sphere may be under attacker control (i.e., the search path cannot be modified by an attacker, but one element of the path can be under attacker control).
Description
