Red Hat Security Advisory: kernel security, bug fix, and enhancement update

1. Implementation · Architecture and Design

   Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.

2. Operation

   Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.

OWASP Cheat Sheets

• Abuse Case (opens in a new tab)

OWASP ASVS 4.0.3

• V8.1.4 (opens in a new tab)
• V13.4.1 (opens in a new tab)
• V11.1.4 (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Architecture and Design

   Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.

2. Architecture and Design

   Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.

3. Architecture and Design · Libraries or Frameworks

   Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

OWASP Cheat Sheets

• Authorization (opens in a new tab)

OWASP ASVS 4.0.3

• V8.3.8 (opens in a new tab)
• V13.4.2 (opens in a new tab)
• V7.2.2 (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Implementation

   The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.

2. Implementation

   When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.

3. Architecture and Design

   Limit the interleaving of operations on files from multiple processes.

OWASP Cheat Sheets

• Abuse Case (opens in a new tab)

OWASP ASVS 4.0.3

• V1.11.3 (opens in a new tab)
• V11.1.6 (opens in a new tab)
• V1.11.2 (opens in a new tab)

Attack patterns

• Leveraging Race Conditions via Symbolic Links (opens in a new tab)
• Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Implementation

   Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free().

2. Implementation

   When programming in C++, consider using smart pointers provided by the boost library to help correctly and consistently manage memory.

3. Architecture and Design · Libraries or Frameworks

   Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Architecture and Design · Implementation

   Temporary files and other supporting resources should be deleted/released immediately after they are no longer needed.

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Implementation

   When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.

2. Implementation

   Do not let the user control the size of the buffer.

3. Implementation

   Validate that the length of the user-supplied data is consistent with the buffer size.

OWASP Cheat Sheets

• XML Security (opens in a new tab)
• Mass Assignment (opens in a new tab)

OWASP ASVS 4.0.3

• V13.3.1 (opens in a new tab)
• V5.1.4 (opens in a new tab)
• V5.1.3 (opens in a new tab)

Attack patterns

• Buffer Overflow via Parameter Expansion (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Requirements

   Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.

2. Architecture and Design

   Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.

3. Architecture and Design

   Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.

OWASP Cheat Sheets

• Abuse Case (opens in a new tab)

OWASP ASVS 4.0.3

• V8.1.4 (opens in a new tab)
• V13.4.1 (opens in a new tab)
• V11.1.4 (opens in a new tab)

Attack patterns

• XML Ping of the Death (opens in a new tab)
• Exponential Data Expansion (opens in a new tab)
• Serialized Data Parameter Blowup (opens in a new tab)
• Serialized Data with Nested Payloads (opens in a new tab)
• Oversized Serialized Data Payloads (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Implementation

   Change the code's logic so that the resource is only closed once. This might require simplifying or refactoring. This fix can be simple to do in small code blocks, but more difficult when multiple closes are buried within complex conditionals.

2. Implementation · Refactoring

   It can be effective to implement a flag that is (1) set when the resource is opened, (2) cleared when it is closed, and (3) checked before closing. This approach can be useful when there are disparate cases in which closes must be performed.

3. Implementation · Refactoring

   When closing a resource, set the resource's associated variable to NULL or equivalent value for the given language. Some APIs will ignore this null value without causing errors.

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Implementation

   When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts "&" characters to "&" for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input…

2. Implementation

   Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles…

3. Implementation · Input Validation

   Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.

Attack patterns

• Overflow Buffers (opens in a new tab)
• Buffer Overflow via Parameter Expansion (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Requirements · Language Selection

   Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

2. Architecture and Design

   Design signal handlers to only set flags, rather than perform complex functionality. These flags can then be checked and acted upon within the main program loop.

3. Implementation

   Only use reentrant functions within signal handlers. Also, use validation to ensure that state is consistent while performing asynchronous actions that affect the state of execution.

OWASP Cheat Sheets

• Abuse Case (opens in a new tab)

OWASP ASVS 4.0.3

• V1.11.2 (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Architecture and Design

   Choose a language that provides automatic memory management.

2. Implementation

   When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

OWASP Cheat Sheets

• XML Security (opens in a new tab)
• Mass Assignment (opens in a new tab)

OWASP ASVS 4.0.3

• V13.3.1 (opens in a new tab)
• V5.1.4 (opens in a new tab)
• V5.1.3 (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Architecture and Design

   Use locking functionality. This is the recommended solution. Implement some form of locking mechanism around code which alters or reads persistent data in a multithreaded environment.

2. Architecture and Design

   Create resource-locking validation checks. If no inherent locking mechanisms exist, use flags and signals to enforce your own blocking scheme when resources are being used by other threads of execution.

OWASP Cheat Sheets

• Abuse Case (opens in a new tab)

OWASP ASVS 4.0.3

• V1.11.2 (opens in a new tab)

Attack patterns

• Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
• Leveraging Race Conditions (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

OWASP Cheat Sheets

• XML Security (opens in a new tab)
• Mass Assignment (opens in a new tab)

OWASP ASVS 4.0.3

• V13.3.1 (opens in a new tab)
• V5.1.4 (opens in a new tab)
• V5.1.3 (opens in a new tab)

Attack patterns

• Pointer Manipulation (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

1. Architecture and Design · Language Selection

   Choose a language that provides automatic memory management.

2. Implementation · Attack Surface Reduction

   When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

OWASP Cheat Sheets

• XML Security (opens in a new tab)
• Mass Assignment (opens in a new tab)

OWASP ASVS 4.0.3

• V13.3.1 (opens in a new tab)
• V5.1.4 (opens in a new tab)
• V5.1.3 (opens in a new tab)

From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).