Common Weakness Enumeration

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CWE-558: Use of getlogin() in Multithreaded Application

Weakness ID: 558
Abstraction: Variant
Status: Draft
Presentation Filter:
+ Description

Description Summary

The application uses the getlogin() function in a multithreaded context, potentially causing it to return incorrect values.

Extended Description

The getlogin() function returns a pointer to a string that contains the name of the user associated with the calling process. The function is not reentrant, meaning that if it is called from another process, the contents are not locked out and the value of the string can be changed by another process. This makes it very risky to use because the username can be changed by other processes, so the results of the function cannot be trusted.

+ Time of Introduction
  • Implementation
+ Applicable Platforms




+ Common Consequences
Access Control

Technical Impact: Modify application data; Bypass protection mechanism; Other

+ Demonstrative Examples

Example 1

The following code relies on getlogin() to determine whether or not a user is trusted. It is easily subverted.

(Bad Code)
Example Language:
pwd = getpwnam(getlogin());
if (isTrustedGroup(pwd->pw_gid)) {
} else {
+ Potential Mitigations

Phase: Architecture and Design

Using names for security purposes is not advised. Names are easy to forge and can have overlapping user IDs, potentially causing confusion or impersonation.

Phase: Implementation

Use getlogin_r() instead, which is reentrant, meaning that other processes are locked out from changing the username.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class227Improper Fulfillment of API Contract ('API Abuse')
Seven Pernicious Kingdoms (primary)700
ChildOfCategoryCategory557Concurrency Issues
Development Concepts (primary)699
ChildOfWeakness BaseWeakness Base663Use of a Non-reentrant Function in a Concurrent Context
Research Concepts (primary)1000
ChildOfCategoryCategory1001SFP Secondary Cluster: Use of an Improper API
Software Fault Pattern (SFP) Clusters (primary)888
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsOften Misused: Authentication
Software Fault PatternsSFP3Use of an improper API
+ Content History
Submission DateSubmitterOrganizationSource
Anonymous Tool Vendor (under NDA)Externally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Applicable_Platforms, Description, Relationships, Taxonomy_Mappings
2009-05-27CWE Content TeamMITREInternal
updated Demonstrative_Examples, Taxonomy_Mappings
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2012-05-11CWE Content TeamMITREInternal
updated Relationships
2012-10-30CWE Content TeamMITREInternal
updated Potential_Mitigations
2014-07-30CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Misused Authentication: getlogin()

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Page Last Updated: May 05, 2017