Home > CAPEC List > CAPEC-31: Accessing/Intercepting/Modifying HTTP Cookies (Version 2.4)  

CAPEC-31: Accessing/Intercepting/Modifying HTTP Cookies

 
Accessing/Intercepting/Modifying HTTP Cookies
Definition in a New Window Definition in a New Window
Attack Pattern ID: 31
Abstraction: Detailed
Status: Draft
Completeness: Complete
+ Description

Summary

This attack relies on the use of HTTP Cookies to store credentials, state information and other critical data on client systems.

The first form of this attack involves accessing HTTP Cookies to mine for potentially sensitive data contained therein.

The second form of this attack involves intercepting this data as it is transmitted from client to server. This intercepted information is then used by the attacker to impersonate the remote user/session.

The third form is when the cookie's content is modified by the attacker before it is sent back to the server. Here the attacker seeks to convince the target server to operate on this falsified information.

Attack Execution Flow

Explore
  1. Obtain copy of cookie:

    The attacker first needs to obtain a copy of the cookie. The attacker may be a legitimate end user wanting to escalate privilege, or could be somebody sniffing on a network to get a copy of HTTP cookies.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Obtain cookie from local filesystem (e.g. C:\Documents and Settings\*\Cookies and C:\Documents and Settings\*\Application Data\Mozilla\Firefox\Profiles\*\cookies.txt in Windows)

    env-Web
    2

    Sniff cookie using a network sniffer such as Wireshark

    env-Web
    3

    Obtain cookie from local memory or filesystem using a utility such as the Firefox Cookie Manager or AnEC Cookie Editor.

    env-Web
    4

    Steal cookie via a cross-site scripting attack.

    env-Web
    5

    Guess cookie contents if it contains predictable information.

    env-Web

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Positive

    Cookies used in web application.

    env-Web
    2Negative

    Cookies not used in web application.

    env-Web

    Outcomes

    IDTypeOutcome Description
    1Success
    Cookie captured by attacker.
    2Failure
    Cookie cannot be captured by attacker.

    Security Controls

    IDTypeSecurity Control Description
    1Preventative
    To prevent network sniffing, cookies should be transmitted over HTTPS and not plain HTTP. To enforce this on the client side, the "secure" flag should be set on cookies (javax.servlet.http.Cookie.setSecure() in Java, secure flag in setcookie() function in php, etc.).
Experiment
  1. Obtain sensitive information from cookie:

    The attacker may be able to get sensitive information from the cookie. The web application developers may have assumed that cookies are not accessible by end users, and thus, may have put potentially sensitive information in them.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    If cookie shows any signs of being encoded using a standard scheme such as base64, decode it.

    env-Web
    2

    Analyze the cookie's contents to determine whether it contains any sensitive information.

    env-Web

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Negative

    Cookie only contains a random session ID (e.g. ASPSESSIONID, JSESSIONID, etc.)

    env-Web
    2Positive

    Cookie contains sensitive information (e.g. "ACCTNO=0234234", or "DBIP=0xaf112a22" -- database server's IP address).

    env-Web
    3Inconclusive

    Cookie's contents cannot be deciphered.

    env-Web

    Outcomes

    IDTypeOutcome Description
    1Success
    Cookie contains sensitive information that developer did not intent the end user to see.
    2Failure
    Cookie does not contain any sensitive information.

    Security Controls

    IDTypeSecurity Control Description
    3Preventative
    Do not store sensitive information in cookies unless they are encrypted such that only the server can decrypt them.
  2. Modify cookie to subvert security controls.:

    The attacker may be able to modify or replace cookies to bypass security controls in the application.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Modify logical parts of cookie and send it back to server to observe the effects.

    env-Web
    2

    Modify numeric parts of cookie arithmetically and send it back to server to observe the effects.

    env-Web
    3

    Modify cookie bitwise and send it back to server to observe the effects.

    env-Web
    4

    Replace cookie with an older legitimate cookie and send it back to server to observe the effects. This technique would be helpful in cases where the cookie contains a "points balance" for a given user where the points have some value. The user may spend his points and then replace his cookie with an older one to restore his balance.

    env-Web

    Outcomes

    IDTypeOutcome Description
    1Success
    Subversion of security controls on server
    2Failure
    Cookie reset by server

    Security Controls

    IDTypeSecurity Control Description
    1Detective
    Web server logs contain many messages indicating that invalid cookies were received from client.
    2Preventative
    Cookies should not contain any information that the user is not allowed to modify, unless that information is never expected to change. In the latter case, the integrity of the cookie should be protected using a digital signature or a message authentication code.
+ Attack Prerequisites
  • Target server software must be a HTTP daemon that relies on cookies.

+ Typical Severity

High

+ Typical Likelihood of Exploit

Likelihood: High

+ Methods of Attack
  • Modification of Resources
  • API Abuse
  • Protocol Manipulation
  • Time and State
+ Examples-Instances

Description

There are two main attack vectors for exploiting poorly protected session variables like cookies. One is the local machine itself which can be exploited directly at the physical level or indirectly through XSS and phishing. In addition, the man in the middle attack relies on a network sniffer, proxy, or other intermediary to intercept the subject's credentials and use them to impersonate the digital subject on the host. The issue is that once the credentials are intercepted, impersonation is trivial for the attacker to accomplish if no other protection mechanisms are in place.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

To overwrite session cookie data, and submit targeted attacks via HTTP

Skill or Knowledge Level: High

Exploiting a remote buffer overflow generated by attack

+ Resources Required

Ability to send HTTP request containing cookie to server

+ Solutions and Mitigations

Design: Use input validation for cookies

Design: Generate and validate MAC for cookies

Implementation: Use SSL/TLS to protect cookie in transit

Implementation: Ensure the web server implements all relevant security patches, many exploitable buffer overflows are fixed in patches issued for the software.

+ Attack Motivation-Consequences
ScopeTechnical ImpactNote
Confidentiality
Read application data
Integrity
Modify application data
Confidentiality
Access_Control
Authorization
Gain privileges / assume identity
+ Injection Vector

HTTP cookie

+ Payload

Malicious input delivered through cookie in HTTP Request.

+ Activation Zone

Client software, such as a browser and its component libraries, or an intermediary

+ Payload Activation Impact

Description

  1. Enables attacker to leverage state stored in cookie
  2. Enables attacker a vector to attack web server and platform
+ Purposes
  • Exploitation
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: HighAvailability Impact: Low
+ Technical Context
Architectural Paradigms
Client-Server
n-Tier
Frameworks
All
Platforms
All
Languages
All
+ References
[R.31.1] [REF-2] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.
+ Content History
Submissions
SubmitterOrganizationDate
[R.31.1][REF-2] Cigital, Inc2007-01-01
Modifications
ModifierOrganizationDateCommentsSource
Gunnar PetersonCigital, Inc2007-02-28Fleshed out content to CAPEC schema from the original descriptions in "Exploiting Software"
Sean BarnumCigital, Inc2007-03-09Review and revise
Richard StruseVOXEM, Inc2007-03-26Review and feedback leading to changes in Name and Description
Sean BarnumCigital, Inc2007-04-13Modified pattern content according to review and feedback
Amit SethiCigital, Inc.2007-10-29Added extended Attack Execution Flow
CAPEC Content TeamThe MITRE Corporation2013-06-21Updated Skill_or_Knowledge_Level and Skill_or_Knowledge_TypeInternal
CAPEC Content TeamThe MITRE Corporation2013-12-18Updated Related_Attack_PatternsInternal
CAPEC Content TeamThe MITRE Corporation2014-02-06Updated Attack_Phases, Examples-InstancesInternal

Page Last Updated: April 10, 2014