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From: Stefan Kangas <stefan@marxist.se>
To: adam plaice <plaice.adam+lists@gmail.com>
Cc: 37656@debbugs.gnu.org, Emacs developers <emacs-devel@gnu.org>
Subject: Re: bug#37656: 27.0.50; Arbitrary code execution with special `mode:'
Date: Wed, 16 Oct 2019 00:27:18 +0200	[thread overview]
Message-ID: <CADwFkmnqfbsEEWkWMA2xnN1O+-JsTcCKrSYv0e3g1+jXrxRY5g@mail.gmail.com> (raw)
In-Reply-To: <CAJw81dZZmX=z-YFDwvEkuWR6xH+cf=mR9h-fcZTphwdXWrA5wg@mail.gmail.com>

adam plaice <plaice.adam+lists@gmail.com> writes:

> Since the bug allows an attacker to execute arbitrary code if the
> victim opens a payload file, and hence opening any file from an
> untrusted source becomes dangerous, it seems to be rather
> serious.

Thanks for raising this here.  I agree that this is serious, and we
should treat it accordingly.

The below patch seems to fix it by disabling the feature it exploits.

A workaround is to add this to your init file:
(setq enable-local-variables nil)

Best regards,
Stefan Kangas


diff --git a/lisp/files.el b/lisp/files.el
index 40807617fa..550227b21a 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3068,7 +3068,7 @@ set-auto-mode
           (if (save-excursion (search-forward ":" end t))
               ;; Find all specifications for the `mode:' variable
               ;; and execute them left to right.
-          (while (let ((case-fold-search t))
+        (when (let ((case-fold-search t))
                        (or (and (looking-at "mode:")
                                 (goto-char (match-end 0)))
                            (re-search-forward "[ \t;]mode:" end t)))



  parent reply	other threads:[~2019-10-15 22:27 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-15 21:05 bug#37656: 27.0.50; Arbitrary code execution with special `mode:' adam plaice
2019-10-15 22:23 ` Clément Pit-Claudel
2019-10-15 22:27 ` Stefan Kangas [this message]
2019-10-15 22:55   ` Stefan Kangas
2019-10-15 23:17     ` Stefan Kangas
2019-10-16  7:58       ` Eli Zaretskii
2019-10-16 11:51         ` Adam Plaice
2019-10-16 17:09           ` Eli Zaretskii
2019-10-16 19:09             ` Phil Sainty
2019-10-16 19:34               ` Eli Zaretskii
2019-10-16 21:02               ` Adam Plaice
2019-10-15 23:17     ` Stefan Kangas
2019-10-16  0:35     ` Adam Plaice
2019-10-16  7:57       ` Eli Zaretskii
2019-10-16  0:55     ` Phil Sainty
2019-10-16  0:55     ` Phil Sainty
2019-10-16  7:59     ` Eli Zaretskii
2019-10-15 22:27 ` Stefan Kangas
2019-10-16  6:43 ` Eli Zaretskii
  -- strict thread matches above, loose matches on Subject: below --
2019-10-08  8:48 bug#37656: 27.0.50; Opening file with specially crafted local variables can cause arbitrary code execution Inbox x adam plaice
2019-10-15 21:05 ` bug#37656: 27.0.50; Arbitrary code execution with special `mode:' adam plaice

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