Common Attack Pattern Enumeration and Classification

Common Attack Pattern Enumeration and Classification

This attack targets a race condition occurring when multiple processes access and manipulate the same resource concurrently and the outcome of the execution depends on the particular order in which the access takes place. The attacker can leverage a race condition by "running the race", modifying the resource and modifying the normal execution flow. For instance a race condition can occur while accessing a file, the attacker can trick the system by replacing the original file with his version and cause the system to read the malicious file.

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.

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 attacker 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;
}

//Source : SAMATE.NIST.GOV : http://samate.nist.gov/SRD/view_testcase.php?login=Guest&;tID=1598