CWE-276 Base Draft Medium likelihood

Incorrect Default Permissions

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of restricting write access to authorized users or processes,…

Definition

What is CWE-276?

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of restricting write access to authorized users or processes, the installation allows unintended actors to modify, delete, or corrupt critical application files.
Incorrect default permissions are a common installation-time mistake where files and folders are created with global read/write access (e.g., world-writable). This often happens because the installer runs with elevated privileges but does not properly lock down the resources it deploys. The result is that any user or service on the system, including low-privilege accounts or malware, can alter configuration files, binaries, or libraries, leading to a direct path for privilege escalation, data tampering, or denial of service. To prevent this, developers and DevOps teams must ensure installation scripts explicitly set secure permissions, adhering to the principle of least privilege. Best practices include removing world-writable bits, assigning ownership to specific service accounts, and validating permissions post-deployment. Automated security scanning tools can also detect and flag overly permissive files as part of a continuous integration pipeline.
Real-world impact

Real-world CVEs caused by CWE-276

  • CVE-2005-1941

    Executables installed world-writable.

  • CVE-2002-1713

    Home directories installed world-readable.

  • CVE-2001-1550

    World-writable log files allow information loss; world-readable file has cleartext passwords.

  • CVE-2002-1711

    World-readable directory.

  • CVE-2002-1844

    Windows product uses insecure permissions when installing on Solaris (genesis: port error).

  • CVE-2001-0497

    Insecure permissions for a shared secret key file. Overlaps cryptographic problem.

  • CVE-1999-0426

    Default permissions of a device allow IP spoofing.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-276

  • Architecture and Design / Operation The architecture needs to access and modification attributes for files to only those users who actually require those actions.
  • Architecture and Design 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.
Detection signals

How to detect CWE-276

Automated Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Inter-application Flow Analysis

Manual Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Automated Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria Web Application Scanner Web Services Scanner Database Scanners

Dynamic Analysis with Manual Results Interpretation High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Host Application Interface Scanner ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer Automated Monitored Execution Forced Path Execution

Manual Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Manual Source Code Review (not inspections) ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source

Automated Static Analysis - Source Code SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Context-configured Source Code Weakness Analyzer

Plexicus auto-fix

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Frequently asked questions

Frequently asked questions

What is CWE-276?

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of restricting write access to authorized users or processes, the installation allows unintended actors to modify, delete, or corrupt critical application files.

How serious is CWE-276?

MITRE rates the likelihood of exploit as Medium — exploitation is realistic but typically requires specific conditions.

What languages or platforms are affected by CWE-276?

MITRE lists the following affected platforms: Not Technology-Specific, ICS/OT.

How can I prevent CWE-276?

The architecture needs to access and modification attributes for files to only those users who actually require those actions. 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…

How does Plexicus detect and fix CWE-276?

Plexicus's SAST engine matches the data-flow signature for CWE-276 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-276?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/276.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-276

CWE-732 Parent

Incorrect Permission Assignment for Critical Resource

This vulnerability occurs when a system grants overly permissive access to a sensitive resource, allowing unauthorized users or processes…

CWE-1004 Sibling

Sensitive Cookie Without 'HttpOnly' Flag

This vulnerability occurs when an application stores sensitive data in a cookie but fails to set the 'HttpOnly' flag, leaving the cookie…

CWE-277 Sibling

Insecure Inherited Permissions

This vulnerability occurs when an application sets default file or directory permissions that are too permissive, and these insecure…

CWE-278 Sibling

Insecure Preserved Inherited Permissions

This vulnerability occurs when a software product copies or extracts files while unintentionally preserving insecure permissions from…

CWE-279 Sibling

Incorrect Execution-Assigned Permissions

This vulnerability occurs when a running application incorrectly changes an object's access permissions, overriding the security settings…

CWE-281 Sibling

Improper Preservation of Permissions

This vulnerability occurs when a system fails to correctly maintain file or object permissions during operations like copying, sharing, or…

CWE-766 Sibling

Critical Data Element Declared Public

This vulnerability occurs when a critical piece of data—like a variable, field, or class member—is mistakenly declared as public when it…

Resources

Further reading

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