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Graph/dynamic-code-execution-boundary-crossing

AntiPattern

Script Invocation Security Boundary

dynamic-code-execution-boundary-crossing

Untrusted script inputs cross a security boundary during dynamic invocation (e.g., Function/load or shell-like execution), so code that was expected to be non-executed still enables compilation, shell behavior, or interpreter access. Outcomes range from unexpected side effects to access via debug/function loaders.

Node Details

Public graph metadata

Updated7/9/2026

Connections

30 linked nodes

MATCHESSolution

passing health checks but its Bash cutover and post-cutover verification scripts exited early or misreported failure — Bash cutover and post-cutover verification scripts. Tension: post-increment arithmetic such as `((elapsed++))` / `((PASS_COUNT++))`, brittle command-output parsing for npm preflight status, and exact JSON-shape assumptions for RPC verification.

MATCHESSolution

This preserves the import-safety property of the guard. Tension: variables visible to all module-level functions.

MATCHESSolution

Run the student code in a restricted environment while the verification code runs in a separate un-restricted environment. Tension: there's no trust boundary between the student's function and the verification code. Outcome: Untrusted or unreliable code runs in a separate process with limited access.

MATCHESSolution

Use a real sandboxing mechanism (e.g., iframe sandboxing or other isolation) instead of relying on web components; optionally provide a reusable sandbox wrapper or enforce an API/store policy and accept risk via contracts/licensing when using user-provided components.

MATCHESSolution

Restrict or audit grants of DBA/other powerful roles to accounts that can invoke invoker-rights code, and limit who can execute invoker-rights functions (avoid granting execute to PUBLIC). Prefer safer security patterns (e.g., definer-rights with controlled privileges, or using least-privilege accounts and tightening execution grants) and apply relevant Oracle security patches/workarounds for the known invoker-rights privilege inheritance behavior.

MATCHESSolution

Untrusted Javascript can be run safely in a typical web browser. — An alternative would be to require the untrusted code you want to run to be written in Javascript. Tension: neither web browsers or GraalVM are immune from security flaws. Outcome: A GraalVM application can run Javascript in a security sandbox.

MATCHESSolution

My solution was to allow only the user the process is running under, and deny NT AUTHORITY\NETWORK. — before the code above. Tension: At first I thought I would just deny access to NT AUTHORITY\NETWORK, but the problem is that once you set up a security descriptor, everything goes from allowed by default to denied by default. Outcome: adding this before the code above.

MATCHESSolution

GitGuardian: for secure code sharing without revealing the actual base code, ideal for sensitive information. — For technical access control irregardless of the NDA. Tension: without revealing the actual base code. Outcome: ideal for sensitive information.

MATCHESSolution

Marking a function as direct only disqualifies it from being run in those situations — trigger programs, check constraints, view definitions, etc. Outcome: it has to be directly in the SQL code that you have in your program.

MATCHESSolution

Using self-elevation — by placing the following at the start of your script. Tension: modifying your script so that it re-invokes itself with elevation on demand. Outcome: by placing the following at the start of your script.

MATCHESSolution

new Function(userCode); — verify (client-side) that the user has entered valid JavaScript code. Tension: Pulling in a Javascript parser (e.g. Acorn or Esprima) is a relatively heavy dependency. Outcome: Parsing/compiling JS code is safe and has no side effects.

MATCHESSolution

`load` is still available. — if I set `os` and `io` to `nil` before running the script. Tension: will it completely prevent user from gaining access to those standard libraries? Outcome: This will allow loading malicious bytecode.

MATCHESSolution

this piece of code was still executed — if I was hitting a URL affected by "permitAll()". Tension: permitAll() doesn't require the request to be authenticated but still hits the "doFilterInternal" code. Outcome: Found the problem.

MATCHESSolution

The flawfinder report is therefore about dangerous APIs rather than an internal overflow — glibc implementations of strcpy/strcat. Tension: bounds checks cannot be added without changing the API.

MATCHESSolution

Stage 2 (startup). Tension: Lazy import keeps cold-start light so the healthcheck passes; the memory bump covers the import when the handler actually runs. Outcome: functions-framework can bind the port.

MATCHESSolution

The changed code invokes undefined behaviour. — Java 25 FFM API. Tension: You can't rely on always getting this behaviour. Outcome: The caller's pointer is passed in to it, but it's never used.

MATCHESSolution

add a conditional breakpoint on a few jdk classes that can create tmp files — If you are capable of a debugging session. Tension: you need to edit the webserver launcher script. Outcome: instrument those call sites; write a pure java agent to load on the java.exe command line.

MATCHESSolution

Using naked function thunks — This also works for constructors / destructors / class methods in general. Tension: with no thunks. Outcome: declare the functions as naked and directly jump to the absolute address where it is defined in the executable.

MATCHESSolution

Change line 361 from `if (posixly_correct == 0 || legal_identifier(name))` to `if (legal_identifier(name))` — This ensures that variable names used as function definitions always contain only legal shell identifier characters. Tension: preventing injection of shell metacharacters. Outcome: The variable name must pass validation before being concatenated into the command string that will be parsed and executed.

MATCHESSolution

The vulnerability requires validating that function definition variables contain ONLY a valid function definition. — Bash 4.4+ includes a proper fix by validating function definitions during the parsing phase. Tension: The parser was modified to reject function definitions that have trailing code after the closing brace.

MATCHESSolution

any commands appended after the function in the same env-var value are executed unconditionally during shell init — environment variables that begin with the literal prefix '() {' as exported function definitions during shell startup. Tension: Env vars are routinely populated from untrusted sources. Outcome: pre-auth RCE.

MATCHESSolution

unbounded memory allocation (DoS) — processing a crafted ELF file.

MATCHESSolution

fixed pre-bash-4.4-beta2 in variables.c:assign_hashcmd lines 1764-1785 — Bash <= 5.0 restricted shell (rbash). Tension: restricted shell (rbash) can be bypassed.

MATCHESSolution

before `ijs_invoke_server(ijsdev->IjsServer)`. Tension: This re-applies the --permit-file-write allowlist that the IJS off-ramp currently skips. Outcome: stop using `execvp("sh","-c",server_cmd)`.

MATCHESSolution

Three-layer defense — during script execution. Outcome: Ran 10 concurrent agents executing ~100 http_script calls each. Zero process crashes after the fix.

MATCHESSolution

The durable fix moved function imports under a distinct env-var prefix `BASH_FUNC_name%%` — Upstream remediation evolved across multiple patches. Tension: ad-hoc string checks proved insufficient. Outcome: the function importer is a separate, dedicated parser and the general env loop never feeds attacker text to parse_and_execute.

MATCHESSolution

Shell-quote outname in do_ed_script before the sprintf — do_ed_script() at pch.c:2399-2403. Tension: avoid shell interpretation entirely.

MATCHESSolution

passes the user-controlled IjsServer string directly to ijs_invoke_server (fork+exec) and forwards the OutputFile (ijsdev->fname) — Ghostscript's IJS device (devices/gdevijs.c, gsijs_open). Tension: with no gp_validate_path / SAFER check. Outcome: an attacker can supply ../ traversal or any absolute path.

MATCHESSolution

CSP-blocked localhost diagnostics — custom activity script. Tension: custom diagnostics fetched a localhost endpoint blocked by CSP. Outcome: Removed forbidden localhost diagnostic fetches from the custom activity script.

MATCHESSolution

Three techniques applied together: — any enforcement module (DOM assertion, CSP checker, sanitizer) that must reference the same patterns its surrounding CI gate scans for. Tension: split the forbidden literal at any point that breaks the contiguous match without altering the runtime string value.

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