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MGS2007: exec denied by sandbox

A spell tried to execute a binary whose resolved path is outside the configured allowlist.

[MGS2007] exec denied: /home/user/.local/bin/exfil

Why

The sandbox denies execution of binaries whose absolute path is not under the workspace, /tmp, or a system library or executable directory (/usr/bin, /usr/local/bin, etc.). This blocks the attack pattern of dropping a small binary into ~/ and running it.

The binary path is the value returned by exec.LookPath, so an unqualified curl resolved from $PATH is checked at /usr/bin/curl, which is allowed.

Resolution

  • Built-in spells: should never trigger this. If they do, file a bug.

  • Third-party spells trying to run a tool you installed locally (e.g. a custom binary under ~/.local/bin): the spell expects an external binary it did not ship. Add the directory to your allowlist:

    sandbox:
  allow:
    - path: ~/.local/bin
      mode: ro

    ro is sufficient: execution requires read access, not write.

  • Malicious spell dropping and running a binary: do not extend the allowlist. This is sandbox working as designed.

sandbox diagnosticsLanding page for the sandbox that confines magus spells to the workspace, plus its MGS2xxx diagnostics for denied reads, writes, execs, and env leaks. MGS2001: path read deniedFires when a spell tries to read a file outside the workspace and outside the configured sandbox allowlist, typically a credential store. MGS2002: path write deniedFires when a spell tries to write to a file outside the workspace and outside the sandbox allowlist, blocking persistence and tampering attacks. Sandbox modelThe threat model and allowlist semantics that magus enforces around spell execution, and how the MGS2xxx diagnostics map onto that model.
MGS2007sandboxsecurityexecpermissionsallowlistbinary
Last updated (b022d75e)
Glossary

Workspace

The magus root directory that owns a set of projects and shared config; the unit magus operates over. See workspace.

Spell

A language/runtime adapter (e.g. go, md) that maps generic targets onto a toolchain's real commands. See spells.

Sandbox

The restricted filesystem and environment a target runs in, so builds stay reproducible and side-effect-free. See sandbox.

CI

An ordinary magusfile-defined target you compose yourself with magus\needs - magus does not hardcode its stages. Magus.RunCI treats it specially only in that it strips the rw charm, it is the anchor magus affected ci keys off, and a selected scope with no project declaring it is a load error rather than a silent no-op. See targets.

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