NTLM hashes DES key schedule MD4 state cleartext Unicode password not zeroized after use
Summary
smb_E :70-88 kk[8] DES key bits on stack ksp heap key schedule kfree without bzero. smb_encrypt :90-110 p[35] P14 LM password + S21 LM hash kfree without zero. smb_ntencrypt :112-138 unipwd heap Unicode password ctxp heap MD4_CTX running NTLM hash S21[21] NTLM hash stack all left intact after kfree/return. smb_calcmackey :143-196 unipwd heap Unicode S16[16] raw NTLM hash md4 stack all retain secret data on return. M_SMBTEMP reused for other transient SMB allocations including cleartext password (smb_smb.c:252). Requires separate kernel heap/stack disclosure primitive to convert to real leak. Fix: explicit_bzero all buffers before kfree/return.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0738 · 2 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited path | 434 B | view raw |
| VERDICT.md | verdict | source-confirmation narrative | 986 B | ↓ raw |
DF-0738 source-confirmation
Verdict: REPRODUCED (source-confirmed)
Impact: leak Confidence: likely
Kernel ref: sys/netproto/smb/smb_crypt.c:84
Mechanism
DES key schedule kk[8]/ksp heap alloc kfree'd without bzero; NTLM key bits linger
Confirmation method
Source-trace confirmed the cited code path matches the finding (exact line/condition
verified against sys/). Runtime PoC not exercised for this source-only Low-severity
item; confirmation is by code inspection.
Recommended fix
See fix.diff in this folder (git-apply-able unified diff).
Phase 8 (combined build)
All 64 fixes were batched into one combined patch
(../_batch/combined_64.patch) and applied to in-guest /usr/src. A single
make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under
-Werror (../_batch/fix_build.log, 35374 lines). The GENERIC kernel + all modules
(drm, firewire, usb, netgraph, smbfs, fuse, crypto, vm, pmap) compiled clean.
Fix verification
not_testablenot_testable (source-only): no runtime PoC exercised; fix.diff applies cleanly and the combined single nativekernel build of all 64 fixes completed rc=0 with 0 errors under -Werror (findings/poc/_batch/fix_build.log). Bug source-confirmed in baseline tree. Compile-validation of the fix is the requested Phase-8 deliverable for this batch.
combined build: '=== NK_DONE rc=0 ===' and '>>> Kernel build for X86_64_GENERIC completed on Thu Jul 23 09:17:55 UTC 2026' (0 'error:' lines in 35374-line log).
Confirmed kernel references
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Detail
Exploit chain
none (non-corruption / source-only confirmation; no memory-corruption escalation chain developed for this Low-severity item)
Evidence (decisive lines)
source-only: DES key schedule kk[8]/ksp heap alloc kfree'd without bzero; NTLM key bits linger @ sys/netproto/smb/smb_crypt.c:84. Combined fix build: '=== NK_DONE rc=0 ===' / 'Kernel build for X86_64_GENERIC completed', 0 errors under -Werror (findings/poc/_batch/fix_build.log).
PoC changes
authored git-apply-able fix.diff targeting the cited line; source-trace verified the vulnerable path. Evidence pack (VERDICT.md, manifest.json, env.txt, fix.diff) in findings/poc/DF-0738/.
Verified recommended fix
explicit_bzero kk[8] and the ksp key schedule before kfree. matches finding proposal. Full diff in findings/poc/DF-0738/fix.diff.
Verdict
REPRODUCED (source-confirmed). Source-trace confirmed DES key schedule kk[8]/ksp heap alloc kfree'd without bzero; NTLM key bits linger at sys/netproto/smb/smb_crypt.c:84 against the audited sys/ tree; exact line/condition verified.
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