What is Compiler Removal of Code to Clear Buffers (CWE-14)?

TL;DR: Compiler Removal of Code to Clear Buffers (CWE-14) is a vulnerability that occurs when sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it’s not read from again. To prevent this vulnerability, you should store sensitive data in a “volatile” memory location if available, configure your compiler not to remove dead stores, and encrypt sensitive data that are used by a software system.

What is Compiler Removal of Code to Clear Buffers?

Compiler Removal of Code to Clear Buffers (CWE-14) is a type of security misconfiguration vulnerability that occurs when sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it’s not read from again. As defined by the MITRE Corporation under CWE-14, and classified by the OWASP Foundation under A09:2021 - Security Misconfiguration…

Quick Summary

Compiler Removal of Code to Clear Buffers (CWE-14) is a vulnerability that can have significant business impacts, including financial losses, compliance issues, and reputational damage. To prevent this vulnerability, you should store sensitive data in a “volatile” memory location if available, configure your compiler not to remove dead stores, and encrypt sensitive data that are used by a software system.

Jump to: Quick Summary · Compiler Removal of Code to Clear Buffers Overview · How Compiler Removal of Code to Clear Buffers Works · Business Impact of Compiler Removal of Code to Clear Buffers · Compiler Removal of Code to Clear Buffers Attack Scenario · How to Detect Compiler Removal of Code to Clear Buffers · How to Fix Compiler Removal of Code to Clear Buffers · Framework-Specific Fixes for Compiler Removal of Code to Clear Buffers · How to Ask AI to Check Your Code for Compiler Removal of Code to Clear Buffers · Compiler Removal of Code to Clear Buffers Best Practices Checklist · Compiler Removal of Code to Clear Buffers FAQ · Vulnerabilities Related to Compiler Removal of Code to Clear Buffers · References · Scan Your Own Site

Compiler Removal of Code to Clear Buffers Overview

What: Compiler Removal of Code to Clear Buffers (CWE-14) is a type of security misconfiguration vulnerability that occurs when sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it’s not read from again.

Why it matters: The consequences of Compiler Removal of Code to Clear Buffers include reading sensitive data that has not been cleared from memory and bypassing protection mechanisms. This can lead to significant business impacts, including financial losses, compliance issues, and reputational damage.

Where it occurs: Compiler Removal of Code to Clear Buffers (CWE-14) can occur in any software system that uses compilers or programming languages.

Who is affected: Any organization that uses software systems that are vulnerable to Compiler Removal of Code to Clear Buffers (CWE-14).

Who is NOT affected: Organizations that do not use software systems that are vulnerable to Compiler Removal of Code to Clear Buffers (CWE-14).

How Compiler Removal of Code to Clear Buffers Works

Root Cause

The root cause of Compiler Removal of Code to Clear Buffers (CWE-14) is the compiler’s optimization of dead stores, which leaves sensitive memory untouched when it’s not read from again.

Attack Flow

1. The attacker exploits the vulnerability by reading sensitive data that has not been cleared from memory.
2. The attacker bypasses protection mechanisms and gains unauthorized access to sensitive data.

Prerequisites to Exploit

• The software system must use compilers or programming languages that are vulnerable to Compiler Removal of Code to Clear Buffers (CWE-14).
• The sensitive data must be stored in a way that allows it to be read from memory without being cleared.

Vulnerable Code

int main() {
  char *buf = malloc(1024);
  strcpy(buf, "Sensitive Data");
  // compiler optimization removes the following line:
  memset(buf, 0, 1024);
  return 0;
}

The vulnerable code above demonstrates how sensitive data can be left in memory without being cleared due to compiler optimizations.

Secure Code

int main() {
  char *buf = malloc(1024);
  strcpy(buf, "Sensitive Data");
  memset(buf, 0, 1024); // secure code clears the buffer immediately
  return 0;
}

The secure code above demonstrates how sensitive data can be cleared from memory immediately after it is no longer needed.

Business Impact of Compiler Removal of Code to Clear Buffers

Confidentiality: The consequences of Compiler Removal of Code to Clear Buffers (CWE-14) include reading sensitive data that has not been cleared from memory, which can lead to unauthorized access and disclosure of sensitive information.

• Financial losses due to theft or exposure of sensitive data
• Compliance issues due to failure to protect sensitive data
• Reputational damage due to breach of trust

Integrity: The consequences of Compiler Removal of Code to Clear Buffers (CWE-14) include modifying sensitive data that has not been cleared from memory, which can lead to unauthorized changes and tampering.

• Financial losses due to theft or exposure of sensitive data
• Compliance issues due to failure to protect sensitive data
• Reputational damage due to breach of trust

Availability: The consequences of Compiler Removal of Code to Clear Buffers (CWE-14) include disrupting the availability of sensitive data, which can lead to downtime and loss of productivity.

• Financial losses due to downtime and lost productivity
• Compliance issues due to failure to protect sensitive data
• Reputational damage due to breach of trust

Compiler Removal of Code to Clear Buffers Attack Scenario

1. The attacker exploits the vulnerability by reading sensitive data that has not been cleared from memory.
2. The attacker bypasses protection mechanisms and gains unauthorized access to sensitive data.
3. The attacker modifies or deletes sensitive data, leading to unauthorized changes and tampering.

How to Detect Compiler Removal of Code to Clear Buffers

Manual Testing

• Review the code for potential vulnerabilities
• Test the code with various inputs to detect any issues
• Use manual testing tools to identify potential vulnerabilities

Automated Scanners (SAST / DAST)

• Use automated scanners to detect potential vulnerabilities in the code
• The scanners can identify potential issues and provide recommendations for remediation

PenScan Detection

• PenScan’s scanner engines are designed to detect potential vulnerabilities in the code, including Compiler Removal of Code to Clear Buffers (CWE-14)
• The scanner engines use a combination of static analysis and dynamic testing to identify potential issues

False Positive Guidance

A finding on code that already uses a real secure-erase mechanism (explicit_bzero(), memset_s(), SecureZeroMemory(), OPENSSL_cleanse(), or a volatile-qualified pointer) instead of a plain memset()/bzero() call is a false positive — the compiler cannot optimize away calls the standard explicitly forbids it from eliminating.

How to Fix Compiler Removal of Code to Clear Buffers

• Store sensitive data in a “volatile” memory location if available
• Configure your compiler not to remove dead stores
• Encrypt sensitive data that are used by a software system

Framework-Specific Fixes for Compiler Removal of Code to Clear Buffers

C/C++

int main() {
  char *buf = malloc(1024);
  strcpy(buf, "Sensitive Data");
  explicit_bzero(buf, 1024); // secure code clears the buffer immediately
  return 0;
}

The secure code above demonstrates how sensitive data can be cleared from memory immediately after it is no longer needed.

Java

public class SecureData {
  public static void main(String[] args) {
    char[] buf = new char[1024];
    System.arraycopy("Sensitive Data".toCharArray(), 0, buf, 0, "Sensitive Data".length());
    Arrays.fill(buf, (char) 0); // secure code clears the buffer immediately
  }
}

The secure code above demonstrates how sensitive data can be cleared from memory immediately after it is no longer needed.

How to Ask AI to Check Your Code for Compiler Removal of Code to Clear Buffers

Review the following C/C++ code block for potential CWE-14 Compiler Removal of Code to Clear Buffers vulnerabilities and rewrite it using explicit_bzero() as the primary fix technique:

int main() {
  char *buf = malloc(1024);
  strcpy(buf, "Sensitive Data");
  // compiler optimization removes the following line:
  memset(buf, 0, 1024);
  return 0;
}

Compiler Removal of Code to Clear Buffers Best Practices Checklist

✅ Store sensitive data in a “volatile” memory location if available ✅ Configure your compiler not to remove dead stores ✅ Encrypt sensitive data that are used by a software system ✅ Use manual testing and automated scanners to detect potential vulnerabilities ✅ Review the code for potential issues and provide recommendations for remediation

Compiler Removal of Code to Clear Buffers FAQ

How does Compiler Removal of Code to Clear Buffers occur?

Compiler Removal of Code to Clear Buffers occurs when sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it’s not read from again.

What are the consequences of Compiler Removal of Code to Clear Buffers?

The consequences of Compiler Removal of Code to Clear Buffers include reading sensitive data that has not been cleared from memory and bypassing protection mechanisms.

How can I detect Compiler Removal of Code to Clear Buffers in my code?

You can detect Compiler Removal of Code to Clear Buffers by using manual testing, automated scanners (SAST / DAST), or PenScan’s detection capabilities.

What are the best practices for preventing Compiler Removal of Code to Clear Buffers?

The best practices for preventing Compiler Removal of Code to Clear Buffers include storing sensitive data in a “volatile” memory location if available, configuring your compiler not to remove dead stores, and encrypting sensitive data that are used by a software system.

What are the related weaknesses to Compiler Removal of Code to Clear Buffers?

The related weakness to Compiler Removal of Code to Clear Buffers is CWE-733: Compiler Optimization Removal or Modification of Security-critical Code (ChildOf).

How can I ask AI to check my code for Compiler Removal of Code to Clear Buffers?

You can ask AI to review your code for potential CWE-14 Compiler Removal of Code to Clear Buffers vulnerabilities and rewrite it using the primary fix technique.

What are the best practices for preventing related weaknesses to Compiler Removal of Code to Clear Buffers?

The best practices for preventing related weaknesses include verifying return values, testing your code, and following secure coding guidelines.

Vulnerabilities Related to Compiler Removal of Code to Clear Buffers

References

• https://cwe.mitre.org/data/definitions/14.html
• https://nvd.nist.gov/

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 Compiler Removal of Code to Clear Buffers and other risks before an attacker does.