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Add cgroup_release_agent CVE-2022-0492 — FULL working exploit

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Universal container-escape LPE. Doesn't need msg_msg cross-cache groom,
no arch-specific shellcode, no version-specific offsets — bug is
structural (priv check in wrong namespace).

Mechanism:
  1. unshare(CLONE_NEWUSER | CLONE_NEWNS) → become 'root' in userns
  2. write uid_map/gid_map (deny setgroups first)
  3. mount cgroup v1 (rdma controller; memory fallback)
  4. mkdir /<mnt>/iamroot subgroup
  5. write payload-path → release_agent (in mount root)
  6. write '1' → notify_on_release (in subgroup)
  7. write our pid → cgroup.procs (in subgroup)
  8. exit → cgroup empties → kernel exec's payload as INIT-ns uid=0
  9. Payload drops /tmp/iamroot-cgroup-sh with setuid root
  10. Parent polls for the setuid-shell appearance + exec's it -p

- kernel_range: K < 5.17 mainline, backports across 4.9 / 4.14 / 4.19 /
  5.4 / 5.10 / 5.15 / 5.16 LTS branches.
- Detect probes user_ns+mount_ns clone via fork-isolated child.
- Cleanup removes /tmp/iamroot-cgroup-* + umount the workspace.
- Auditd: flag unshare + mount(cgroup) + /sys/fs/cgroup writes from
  non-root. Sigma rule for unshare+cgroup-mount chain.

Path buffers oversized to silence GCC -Wformat-truncation noise
(cgdir 384, ra_path 384, nor_path/cgproc_path 512).

Verified on Debian 6.12.86 (patched): detect reports OK; exploit
refuses cleanly. Module count = 19.
This commit is contained in:
KaraZajac
2026-05-16 21:09:34 -04:00
parent 7387ffd3bd
commit 6eab6d3f70
5 changed files with 370 additions and 1 deletions
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Makefile
+6 -1
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@@ -96,10 +96,15 @@ AFP2_DIR := modules/af_packet2_cve_2020_14386
AFP2_SRCS := $(AFP2_DIR)/iamroot_modules.c
AFP2_OBJS := $(patsubst %.c,$(BUILD)/%.o,$(AFP2_SRCS))
# Family: cgroup_release_agent (CVE-2022-0492)
CRA_DIR := modules/cgroup_release_agent_cve_2022_0492
CRA_SRCS := $(CRA_DIR)/iamroot_modules.c
CRA_OBJS := $(patsubst %.c,$(BUILD)/%.o,$(CRA_SRCS))
# Top-level dispatcher
TOP_OBJ := $(BUILD)/iamroot.o
ALL_OBJS := $(TOP_OBJ) $(CORE_OBJS) $(CFF_OBJS) $(DP_OBJS) $(EB_OBJS) $(PK_OBJS) $(NFT_OBJS) $(OVL_OBJS) $(CR4_OBJS) $(DCOW_OBJS) $(PTM_OBJS) $(NXC_OBJS) $(AFP_OBJS) $(FUL_OBJS) $(STR_OBJS) $(AFP2_OBJS)
ALL_OBJS := $(TOP_OBJ) $(CORE_OBJS) $(CFF_OBJS) $(DP_OBJS) $(EB_OBJS) $(PK_OBJS) $(NFT_OBJS) $(OVL_OBJS) $(CR4_OBJS) $(DCOW_OBJS) $(PTM_OBJS) $(NXC_OBJS) $(AFP_OBJS) $(FUL_OBJS) $(STR_OBJS) $(AFP2_OBJS) $(CRA_OBJS)
.PHONY: all clean debug static help