Files

T

leviathan f03efbff13 Phase 3: EntryBleed module — working stage-1 kbase leak brick

- modules/entrybleed_cve_2023_0458/ (promoted out of _stubs):
  - iamroot_modules.{c,h}: full EntryBleed primitive (rdtsc_start/end
    + prefetchnta + KASLR-slot timing sweep) wired into the standard
    iamroot_module interface. x86_64 only; ARM/other gracefully
    return IAMROOT_PRECOND_FAIL.
  - detect(): reads /sys/.../vulnerabilities/meltdown to decide
    KPTI status. Mitigation: PTI → VULNERABLE. Not affected → OK.
  - exploit(): sweeps the 16MiB KASLR range, prints leaked kbase
    (and KASLR slide). JSON-mode emits {"kbase":"0x..."} to stdout.
  - entrybleed_leak_kbase_lib(off) declared as a public library
    helper so future LPE chains needing a stage-1 leak can just
    #include the module's header and call it.
  - entry_SYSCALL_64 slot offset overridable via
    IAMROOT_ENTRYBLEED_OFFSET (default 0x5600000 for lts-6.12.x).

- __always_inline fallback added since glibc/Linux-kernel macro
  isn't universal; module now builds clean under macOS clangd lint
  and on musl.

- iamroot.c registers entrybleed alongside the other families;
  Makefile gains it as a separate object set.

Verified end-to-end on kctf-mgr (Debian 6.12.86):
  iamroot --exploit entrybleed --i-know
  → [+] entrybleed: leaked kbase = 0xffffffff8d800000

This is the FIRST WORKING-EXPLOIT module in IAMROOT (5
copy_fail_family modules wrap existing code from DIRTYFAIL;
dirty_pipe is detect-only). EntryBleed is x86_64 stage-1 brick
that future chains can compose.

2026-05-16 19:55:22 -04:00

1.9 KiB

Raw Blame History

EntryBleed — CVE-2023-0458

⚪ PLANNED stub module. See ../../ROADMAP.md Phase 3.

Summary

KPTI's user-space-mapped entry trampoline is detectable via prefetchnta timing, leaking the kernel base address (defeats KASLR). Universal across modern x86_64 kernels with KPTI; only partial mitigations have shipped upstream.

Why this is here

EntryBleed is not a standalone LPE. It's a stage-1 leak primitive that future LPE modules can call when they need a kbase. Bundling it as a module:

Lets other modules #include "core/entrybleed.h" and call entrybleed_leak_kbase() when they need KASLR defeat
Ships defensive detection rules for prefetchnta-timing-attack patterns (useful for hardened environments)
Documents the technique with a clear writeup so users understand what "stage-1" means in the broader chain

Empirical status on recent kernels

Verified 2026-05-16: works 5/5 on lts-6.12.88 (no anti-EntryBleed mitigation configured). See security-research/findings/audit_io_uring_2026-05-16_poc_attempt.md and the EntryBleed test code at SKYFALL/bugs/leak_write_modprobe_2026-05-16/exploit.c lines ~73-150.

Upstream patches

There is no single canonical patch. Partial mitigations include:

CONFIG_RANDOMIZE_KSTACK_OFFSET (per-syscall kernel stack jitter)
Some KPTI hardening discussions on lkml, no merged fix as of lts-6.12.88
The community position remains that "KASLR is best-effort, not a security boundary"

Implementation plan

Lift the proven EntryBleed code from SKYFALL/bugs/leak_write_modprobe_2026-05-16/exploit.c into module.c here
Expose as both a CLI mode (iamroot --leak-kbase) and as a library helper (uint64_t entrybleed_leak_kbase(void))
Detection rules: timing-attack pattern flags, perf-counter anomaly detection (informational — these are hard to make precise without false positives)

Not started yet

Phase 3.

1.9 KiB Raw Blame History