Breaking Claude Code Opus 5 Auto Mode

(embracethered.com)

81 points | by Recursing 3 hours ago

10 comments

  • colinmarc 0 minutes ago
    What's interesting to me about this is that it targets Claude's specific tics. Anthropic has created model that reliably reaches for the same tools (yes, and phrases; `python -c` is a load-bearing tool for it). Everyone gets the same model, so by learning the model's behavioral patterns you can target it better.
  • mcherm 2 minutes ago
    Why is the first step needed? What does the use of WGet (rather than curl) do to block this attack?
  • Phemist 15 minutes ago
    This default-to-auto-mode and the misleading marketing is begging for a class action once damages accumulate. Especially considering the Auto Mode even can actively prevent the clean-up!
  • rcxdude 5 minutes ago
    I would not really call this a prompt injection attack, since it doesn't really hijack the agent to become malicious (something the article does discuss later on). It's more a trojan that's aimed at tricking Claude specifically.
  • comboy 37 minutes ago
    Interesting attack, very nicely designed. Not sure if it's much related to the auto mode itself though.
    • kevsim 36 minutes ago
      The point is that auto mode gives people a false sense of security that leads them to believe they don't need to run Claude in a proper sandbox. This same attack running in a sandbox (even in YOLO mode) would be comparatively harmless.
    • yeputons 9 minutes ago
      I don’t think it’s related to the auto mode at all. It would work perfectly in the manual mode. It does not even need Claude: just give a human a similar archive and hope they run some simple Python from the directory at least once. And make sure there are lots of files do they don’t notice a weird .py around
  • hahn-kev 7 minutes ago
    As a non Python dev this seems like very surprising behavior for a system library to be modified by just having a file with a specific name in the same folder.
    • rcxdude 4 minutes ago
      You would get a similar thing in C and C++ with a system header in a library directory (maybe some compilers would warn on such a thing?). Most languages don't privilege their standard libraries in a way that would prevent this.
  • nasretdinov 35 minutes ago
    That's an interesting technique! I'd also like to point out that there's something odd with the page itself too, my phone got really hot while I was reading the page, and drained a significant amount of battery charge as well.
  • julien_dev 1 hour ago
    I'm quite surprised that we are not seeing something like this more in the wild. Quite concerning
    • rcxdude 12 minutes ago
      It's not that far off a typical trojan, just one tailored to Claude's habits. A lot of the same limits apply.
    • mkurz 40 minutes ago
      Maybe it is used in the wild, but we just don't know.
  • bewareofscams 14 minutes ago
    > Boris Cherny from Anthropic recently posted that layered defenses could reduce indirect prompt injection on unseen attacks to approximately zero.

    > I got attack success rates up to 80% using a small sample size.

    Snake oil salesman misrepresents the data. Color me surprised! /s