Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-548 Variant Draft
Exposure of Information Through Directory Listing
This vulnerability occurs when a web server is misconfigured to display a full list of files within a directory instead of serving a default web page, unintentionally exposing sensitive resources to…
Definition
What is CWE-548?
This vulnerability occurs when a web server is misconfigured to display a full list of files within a directory instead of serving a default web page, unintentionally exposing sensitive resources to anyone who visits the URL.
Directory listings happen when a web server (like Apache, Nginx, or IIS) can't find a default index file (e.g., index.html) and its configuration allows it to show the folder's contents. This acts as a roadmap for attackers, revealing backup files, configuration scripts, temporary uploads, or administrative interfaces that were never meant to be public. A simple manual check or a DAST scan can easily uncover this issue.
Prevention involves configuring your server to disable directory listings and always ensuring a default index page exists. For developers, this means checking server configuration files for directives like 'Options -Indexes' in Apache or 'autoindex off' in Nginx. Managing this at scale across hundreds of services is difficult; an ASPM like Plexicus can help you continuously track and automatically flag these misconfigurations across your entire application portfolio.
Real-world impact
Real-world CVEs caused by CWE-548
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 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.
// 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
// 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-548
- Architecture and Design / System Configuration Recommendations include restricting access to important directories or files by adopting a need to know requirement for both the document and server root, and turning off features such as Automatic Directory Listings that could expose private files and provide information that could be utilized by an attacker when formulating or conducting an attack.
Detection signals
How to detect CWE-548
CWE-548
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Frequently asked questions What is CWE-548?
How serious is CWE-548?
What languages or platforms are affected by CWE-548?
How can I prevent CWE-548?
How does Plexicus detect and fix CWE-548?
Where can I learn more about CWE-548?
Frequently asked questions
What is CWE-548?
This vulnerability occurs when a web server is misconfigured to display a full list of files within a directory instead of serving a default web page, unintentionally exposing sensitive resources to anyone who visits the URL.
How serious is CWE-548?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-548?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-548?
Recommendations include restricting access to important directories or files by adopting a need to know requirement for both the document and server root, and turning off features such as Automatic Directory Listings that could expose private files and provide information that could be utilized by an attacker when formulating or conducting an attack.
How does Plexicus detect and fix CWE-548?
Plexicus's SAST engine matches the data-flow signature for CWE-548 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-548?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/548.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-548
CWE-497 Parent
Exposure of Sensitive System Information to an Unauthorized Control Sphere
This vulnerability occurs when an application unintentionally reveals sensitive details about its underlying system, such as file paths,…
CWE-214 Sibling
Invocation of Process Using Visible Sensitive Information
This vulnerability occurs when a process is started with sensitive data, such as passwords or API keys, passed directly in its…
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