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Graph/untrusted-dynamic-eval-misuse

AntiPattern

Dynamic Code Execution Limits

untrusted-dynamic-eval-misuse

Untrusted dynamic evaluation mechanisms (e.g., Function/load/eval-like APIs) can silently shift from “run code” to “compile/resolve” semantics, while other execution paths (shell invocation, Lua package references) reintroduce side effects. The risk is unexpected code execution or capability exposure.

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Updated7/10/2026

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30 linked nodes

MATCHESSolution

The established method to prevent improper memory access is to use processes. — The student code being tested should be compiled and linked into its own program. Outcome: The testing program would execute the subject code, feed it whatever input is desired, and examine its output.

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

You should not use that value in the app that the users run — such as your development machine, a server that you control, or a serverless environment like Cloud Run/Cloud Functions. Tension: If a value is meant to be a secret from the users of your app. Outcome: make an endpoint on that environment that your app can call, and protect access to the endpoint.

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

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

Use smaller scopes where it improves correctness (e.g., declare loop counters inside the loop, such as `for(int i = 0; ...)`), and rely on the compiler/JIT for resource efficiency; avoid broader scopes to reduce the chance of stale or invalid variable usage.

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Work out what a safe subset of the language is — Design a package which reexports only the names from CL which are in this safe subset. Tension: there are snares everywhere. Outcome: Design a safe reader. This should at least prevent read-time evaluation.

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you're going to need to define your syntax very strictly, implement your own parser then hand off the final expression to eval. — if you allow anything which is not an arithmentic operator or a number to be 'eval'ed. Tension: the code is exploitable. Outcome: hand off the final expression to eval.

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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.

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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

you either need to call it (just once is enough), or disable lazy compilation. — If you care about the actual tiering-up of the function. Tension: you need to spend a sufficient amount of time in the unoptimized version of the function. Outcome: Use the `--wasm-tiering-budget` flag to set a lower budget for testing.

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

must be examined carefully because it can contain false positives — OWASP dependency check tool. Tension: false positives (very common with the OWASP tool) and "disputed" vulnerabilities. Outcome: must be examined carefully.

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.

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Regularly checking your codebase against common vulnerabilities — by utilizing OWASP, CWE, etc. Tension: security score might not be sufficient for tomorrow.

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only recompilation could grant a success. — Core Isolation. Tension: the alignment is required to be 0x1000. Outcome: Only recompilation will fix this.

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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.

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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.

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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

This feature is useful if you only need the side effect of evaluating an expression — if the syntax requires you to declare a variable. Tension: but you don't actually need that variable. Outcome: you can replace the variable name with the keyword `_`.

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

Outcome: This code compiles and runs as expected.

MATCHESSolution

Ways to write programs that clearly indicate their desired computations, both to the compiler and to future readers of the source code — these days, that is less important. Tension: it remains important to give programmers expressive power. Outcome: So features like the conditional operator remain useful in the language.

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.

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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.

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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

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

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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