What is Reliance on Data/Memory Layout (CWE-188)?

TL;DR: Reliance on Data/Memory Layout (CWE-188) occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior. This can be prevented by fully specifying protocol layout unambiguously.

At-a-Glance

What is Reliance on Data/Memory Layout?

Reliance on Data/Memory Layout (CWE-188) is a type of vulnerability that occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior. As defined by the MITRE Corporation under CWE-188, and classified by the OWASP Foundation under None.

Quick Summary

Reliance on Data/Memory Layout (CWE-188) is a type of vulnerability that occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior. This can result in modifications to memory and reading of sensitive information, potentially leading to confidentiality and integrity breaches.

Jump to: Quick Summary · Reliance on Data/Memory Layout Overview · How Reliance on Data/Memory Layout Works · Business Impact of Reliance on Data/Memory Layout · Reliance on Data/Memory Layout Attack Scenario · How to Detect Reliance on Data/Memory Layout · How to Fix Reliance on Data/Memory Layout · Framework-Specific Fixes for Reliance on Data/Memory Layout · How to Ask AI to Check Your Code for Reliance on Data/Memory Layout · Reliance on Data/Memory Layout Best Practices Checklist · Reliance on Data/Memory Layout FAQ · Vulnerabilities Related to Reliance on Data/Memory Layout · References · Scan Your Own Site

Reliance on Data/Memory Layout Overview

Reliance on Data/Memory Layout (CWE-188) is a type of vulnerability that occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.

What

Reliance on Data/Memory Layout (CWE-188) occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level.

Why it matters

This can result in modifications to memory and reading of sensitive information, potentially leading to confidentiality and integrity breaches.

Where it occurs

Reliance on Data/Memory Layout (CWE-188) can occur in various protocols and network communications.

Who is affected

Any product that relies on protocol data or memory layout can be affected by Reliance on Data/Memory Layout (CWE-188).

Who is NOT affected

Products that do not rely on protocol data or memory layout are not affected by Reliance on Data/Memory Layout (CWE-188).

How Reliance on Data/Memory Layout Works

Reliance on Data/Memory Layout (CWE-188) occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.

Root Cause

The root cause of Reliance on Data/Memory Layout (CWE-188) is the product’s reliance on protocol data or memory layout.

Attack Flow

1. The attacker sends a malicious request to the product.
2. The product processes the request and makes invalid assumptions about how protocol data or memory is organized at a lower level.
3. The product’s behavior is affected, resulting in unintended program behavior.

Prerequisites to Exploit

• The attacker must send a malicious request to the product.
• The product must rely on protocol data or memory layout.

Vulnerable Code

struct Header {
    char type;
    int length;
};

void serialize(struct Header *h, unsigned char *buf) {
    memcpy(buf, h, sizeof(struct Header));
}

This code demonstrates Reliance on Data/Memory Layout (CWE-188): memcpy copies the struct’s raw in-memory bytes, which depend on compiler-specific padding, alignment, and endianness. The serialized bytes will differ across compilers/platforms, breaking anything that reads them elsewhere.

Secure Code

void serialize(struct Header *h, unsigned char *buf) {
    buf[0] = (unsigned char)h->type;
    buf[1] = (h->length >> 24) & 0xFF;
    buf[2] = (h->length >> 16) & 0xFF;
    buf[3] = (h->length >> 8) & 0xFF;
    buf[4] = h->length & 0xFF;
}

This code demonstrates a secure way to serialize the struct by explicitly writing each field’s bytes in a fixed, documented order, avoiding any dependency on the compiler’s memory layout.

Business Impact of Reliance on Data/Memory Layout

Reliance on Data/Memory Layout (CWE-188) can result in modifications to memory and reading of sensitive information, potentially leading to confidentiality and integrity breaches. This can have significant business impacts, including:

• Financial losses due to data breaches
• Compliance issues due to regulatory requirements
• Reputation damage due to public disclosure of vulnerabilities

Reliance on Data/Memory Layout Attack Scenario

1. The attacker sends a malicious request to the product.
2. The product processes the request and makes invalid assumptions about how protocol data or memory is organized at a lower level.
3. The product’s behavior is affected, resulting in unintended program behavior.

How to Detect Reliance on Data/Memory Layout

Reliance on Data/Memory Layout (CWE-188) can be detected through manual testing and automated scanners (SAST / DAST).

Manual Testing

• Review the product’s code for reliance on protocol data or memory layout.
• Test the product with malicious requests to simulate Reliance on Data/Memory Layout (CWE-188).

Automated Scanners (SAST / DAST)

• Use SAST tools to analyze the product’s code for potential vulnerabilities.
• Use DAST tools to test the product’s behavior under various scenarios.

PenScan Detection

PenScan’s scanner engines actively test for Reliance on Data/Memory Layout (CWE-188).

False Positive Guidance

To avoid false positives, ensure that the product’s code is properly validated and sanitized before processing requests.

How to Fix Reliance on Data/Memory Layout

Reliance on Data/Memory Layout (CWE-188) can be fixed by fully specifying protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar).

Framework-Specific Fixes for Reliance on Data/Memory Layout

• In C or C++, use memset() to securely clear memory.
• In Java, use the SecureZeroMemory() method to securely clear memory.

How to Ask AI to Check Your Code for Reliance on Data/Memory Layout

Review the following [language] code block for potential CWE-188 Reliance on Data/Memory Layout vulnerabilities and rewrite it using primary fix technique: [paste code here]

Reliance on Data/Memory Layout Best Practices Checklist

✅ Fully specify protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar). ✅ Never allow computing memory addresses as offsets from another memory address. ✅ Test that the implementation properly handles each case in the protocol grammar.

Reliance on Data/Memory Layout FAQ

How is Reliance on Data/Memory Layout defined?

Reliance on Data/Memory Layout (CWE-188) is a type of vulnerability that occurs when the product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.

What are the common consequences of Reliance on Data/Memory Layout?

The common consequences of Reliance on Data/Memory Layout include modifications to memory and reading of sensitive information.

How can I prevent Reliance on Data/Memory Layout?

One way to prevent Reliance on Data/Memory Layout is to fully specify protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar).

What are the potential mitigations for Reliance on Data/Memory Layout?

The potential mitigations for Reliance on Data/Memory Layout include never allowing computing memory addresses as offsets from another memory address and testing that the implementation properly handles each case in the protocol grammar.

Can you provide an example of vulnerable code for Reliance on Data/Memory Layout?

Yes, here is an example of vulnerable code: os.chdir(path) without any protective checks.

How can I detect Reliance on Data/Memory Layout?

You can detect Reliance on Data/Memory Layout through manual testing and automated scanners (SAST / DAST).

What are the best practices for preventing Reliance on Data/Memory Layout?

Some best practices include fully specifying protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar), and never allowing computing memory addresses as offsets from another memory address.

Vulnerabilities Related to Reliance on Data/Memory Layout

References

• https://cwe.mitre.org/data/definitions/188.html
• None
• None
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Reliance on Data/Memory Layout and other risks before an attacker does.