This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.
High
High

1
Explore
The adversary explores to gauge what level of access they have.

2
Experiment
The adversary confirms access to a resource on the target host. The adversary confirms ability to modify the targeted resource.

3
Exploit
The adversary decides to leverage the race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary can replace the resource and cause an escalation of privilege.

A resource is access/modified concurrently by multiple processes.
The adversary is able to modify resource.
A race condition exists while accessing a resource.

This attack can get sophisticated since the attack has to occur within a short interval of time.

Integrity
Modify Data

Confidentiality
Access Control
Authorization
Gain Privileges

Confidentiality
Integrity
Availability
Alter Execution Logic

Confidentiality
Read Data

Availability
Resource Consumption
Denial of Service

Use safe libraries to access resources such as files.
Be aware that improper use of access function calls such as chown(), tempfile(), chmod(), etc. can cause a race condition.
Use synchronization to control the flow of execution.
Use static analysis tools to find race conditions.
Pay attention to concurrency problems related to the access of resources.

The Net Direct client for Linux before 6.0.5 in Nortel Application Switch 2424, VPN 3050 and 3070, and SSL VPN Module 1000 extracts and executes files with insecure permissions, which allows local users to exploit a race condition to replace a world-writable file in /tmp/NetClient and cause another user to execute arbitrary code when attempting to execute this client, as demonstrated by replacing /tmp/NetClient/client. See also: CVE-2007-1057

The following code illustrates a file that is accessed multiple times by name in a publicly accessible directory. A race condition exists between the accesses where an adversary can replace the file referenced by the name.
include <sys/types.h>include <fcntl.h>include <unistd.h>
define FILE "/tmp/myfile"define UID 100
void test(char *str){int fd;fd = creat(FILE, 0644);if(fd == -1)return;
chown(FILE, UID, -1); /* BAD */close(fd);
}
int main(int argc, char **argv){char *userstr;if(argc > 1) {userstr = argv[1];test(userstr);
}return 0;
}
[REF-107]

CAPEC Content Team
The MITRE Corporation
2014-06-23

CAPEC Content Team
The MITRE Corporation
2017-01-09
Updated Related_Attack_Patterns

CAPEC Content Team
The MITRE Corporation
2017-08-04
Updated Attack_Phases, Attack_Prerequisites, Description Summary, Examples-Instances

CAPEC Content Team
The MITRE Corporation
2018-07-31
Updated References

CAPEC Content Team
The MITRE Corporation
2019-09-30
Updated @Abstraction

CAPEC Content Team
The MITRE Corporation
2020-07-30
Updated Example_Instances, Execution_Flow, Related_Attack_Patterns

CAPEC Content Team
The MITRE Corporation
2022-09-29
Updated Example_Instances