(conda) Constructor is a tool that enables users to create installers for conda package collections. In versions 3.12.2 and below, the installation directory inherits permissions from its parent directory. Outside of restricted directories, the permissions are very permissive and often allow write access by authenticated users. Any logged in user can make modifications during the installation for both single-user and all-user installations. This constitutes a local attack vector if the installation is in a directory local users have access to. For single-user installations in a shared directory, these permissions persist after the installation. This issue is fixed in version 3.13.0.
Weakness
The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list 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. This 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, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
References