Ensure pull_request_target workflows do not check out or run untrusted pull request code

CríticaNivel 1Automatizadasupply-chain

Descripción

pull_request_target runs in the context of the base repository with a write-scoped GITHUB_TOKEN and access to secrets. Checking out the PR head (github.event.pull_request.head.sha/ref, github.head_ref, refs/pull/*) and building it lets any fork author execute code with those privileges ('pwn request'). The audit flags workflow files that use pull_request_target and reference the PR head anywhere; review flagged files manually.

Cómo se verifica

Método de auditoría: Comando de shell

shell

top=$(git rev-parse --show-toplevel 2>/dev/null) || exit 1
cd "$top" || exit 1
wf=$(git ls-files -- '.github/workflows/*.yml' '.github/workflows/*.yaml' 2>/dev/null) || exit 1
bad=$(printf '%s\n' "$wf" | while IFS= read -r f; do
  [ -n "$f" ] || continue
  if grep -qE '^[^#]*pull_request_target' "$f" &&
     grep -qE '^[^#]*(github\.event\.pull_request\.head\.(sha|ref|repo)|github\.event\.pull_request\.merge_commit_sha|github\.head_ref|refs/pull/)' "$f"; then
    echo "$f"
  fi
done)
if [ -z "$bad" ]; then echo compliant; else echo "pull_request_target workflows that reference the untrusted PR head:"; printf '%s\n' "$bad"; fi

Salida esperada: compliant

Cómo se corrige

Método de corrección: Guía o parche de infraestructura

Switch the workflow to the pull_request trigger (no secrets, read-only token), or split it: build untrusted code under pull_request and upload artifacts, then process them in a separate workflow_run job that never executes PR code. If pull_request_target is unavoidable, do not check out the head ref and set permissions: read-all.

Propiedades

Sistemas operativos: Cualquiera
Etiquetas: supply-chainbuild-pipelinegithub-actions
Referencia: CIS Software Supply Chain Security Guide Benchmark v1.0.0 - Build Pipelines - isolate untrusted code from pipeline secrets (verify section number for your release)

Verificar este host

Ejecute esto en un equipo que tenga permiso para auditar. El escaneo es de solo lectura.

shell

tmaegis scan --target supply-chain