COMMON WEAKNESS ENUMERATIONIncomplete

CWE-212

Improper Removal of Sensitive Information Before Storage or Transfer

The product stores, transfers, or shares a resource that contains sensitive information, but it does not properly remove that information before the product makes the resource available to unauthorized actors.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product stores, transfers, or shares a resource that contains sensitive information, but it does not properly remove that information before the product makes the resource available to unauthorized actors.

Extended description

Resources that may contain sensitive data include documents, packets, messages, databases, etc. While this data may be useful to an individual user or small set of users who share the resource, it may need to be removed before the resource can be shared outside of the trusted group. The process of removal is sometimes called cleansing or scrubbing. For example, a product for editing documents might not remove sensitive data such as reviewer comments or the local pathname where the document is stored. Or, a proxy might not remove an internal IP address from headers before making an outgoing request to an Internet site.

Root cause

How and when does the problem arise?

Lifecycle phase

Architecture and Design

Lifecycle phase

Implementation

REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Lifecycle phase

Operation

Risk

What does successful exploitation lead to?

Read Files or DirectoriesRead Application Data

Affected security scopes: Confidentiality

Sensitive data may be exposed to an unauthorized actor in another control sphere. This may have a wide range of secondary consequences that will depend on what data is exposed. One possibility is the exposure of system data - such as file locations, software versions, or device data - that allow an attacker to craft a specific, more effective attack. Alternately, insufficient redaction of Private Personal Information (PPI), Personally Identifiable Information (PII), or other types of information might not harm the secure operation of the product itself, but could be violations of expectations by the product's users.

Defence

How is it prevented and fixed?

Requirements

Security requirement

Detail
Clearly specify which information should be regarded as private or sensitive, and require that the product offers functionality that allows the user to cleanse the sensitive information from the resource before it is published or exported to other parties.

Architecture and Design

Separation of Privilege

Detail
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 the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Implementation · Operation

Attack Surface Reduction

Detail
Some tools can automatically analyze documents to redact, strip, or "sanitize" private information, although some human review might be necessary. Tools may vary in terms of which document formats can be processed. When calling an external program to automatically generate or convert documents, invoke the program with any available options that avoid generating sensitive metadata. Some formats have well-defined fields that could contain private data, such as Exchangeable image file format (Exif), which can contain potentially sensitive metadata such as geolocation, date, and time [REF-1515] [REF-1516].

Implementation

Attack Surface Reduction

Detail
Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible.

Effectiveness: Defense in Depth

This makes it easier to spot places in the code where data is being used that is unencrypted.

Implementation

Implementation-phase defence

Detail
Avoid errors related to improper resource shutdown or release (CWE-404), which may leave the sensitive data within the resource if it is in an incomplete state.

Verification

How is it detected?

Automated Static Analysis

Tools are available to analyze documents (such as PDF, Word, etc.) to look for private information such as names, addresses, etc.