CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-488: Exposure of Data Element to Wrong Session

Weakness ID: 488
Abstraction: Variant
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.
+ Extended Description

Data can "bleed" from one session to another through member variables of singleton objects, such as Servlets, and objects from a shared pool.

In the case of Servlets, developers sometimes do not understand that, unless a Servlet implements the SingleThreadModel interface, the Servlet is a singleton; there is only one instance of the Servlet, and that single instance is used and re-used to handle multiple requests that are processed simultaneously by different threads. A common result is that developers use Servlet member fields in such a way that one user may inadvertently see another user's data. In other words, storing user data in Servlet member fields introduces a data access race condition.

+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1018Manage User Sessions
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass269Improper Privilege Management
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Confidentiality

Technical Impact: Read Application Data

+ Demonstrative Examples

Example 1

The following Servlet stores the value of a request parameter in a member field and then later echoes the parameter value to the response output stream.

(bad)
Example Language: Java 
public class GuestBook extends HttpServlet {
String name;

protected void doPost (HttpServletRequest req, HttpServletResponse res) {
name = req.getParameter("name");
...
out.println(name + ", thanks for visiting!");

}

}

While this code will work perfectly in a single-user environment, if two users access the Servlet at approximately the same time, it is possible for the two request handler threads to interleave in the following way: Thread 1: assign "Dick" to name Thread 2: assign "Jane" to name Thread 1: print "Jane, thanks for visiting!" Thread 2: print "Jane, thanks for visiting!" Thereby showing the first user the second user's name.

+ Potential Mitigations

Phase: Architecture and Design

Protect the application's sessions from information leakage. Make sure that a session's data is not used or visible by other sessions.

Phase: Testing

Use a static analysis tool to scan the code for information leakage vulnerabilities (e.g. Singleton Member Field).

Phase: Architecture and Design

In a multithreading environment, storing user data in Servlet member fields introduces a data access race condition. Do not use member fields to store information in the Servlet.
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsData Leaking Between Users
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
7 Pernicious Kingdoms
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Other_Notes, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-10-29CWE Content TeamMITRE
updated Description, Other_Notes
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-12-13CWE Content TeamMITRE
updated Relationships
2011-03-29CWE Content TeamMITRE
updated Name
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships, Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Data Leaking Between Users
2011-03-29Data Leak Between Sessions

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Page Last Updated: November 14, 2017