Re: CVE-2024-28085: Escape sequence injection in util-linux wall

                							

                <!--X-Body-Begin-->
<!--X-User-Header-->

oss-sec
mailing list archives
<!--X-User-Header-End-->
<!--X-TopPNI-->

By Date

By Thread

</form>

<!--X-TopPNI-End-->
<!--X-MsgBody-->
<!--X-Subject-Header-Begin-->
Re: CVE-2024-28085: Escape sequence injection in util-linux wall

<!--X-Subject-Header-End-->
<!--X-Head-of-Message-->

From: Demi Marie Obenour &lt;demi () invisiblethingslab com&gt;

Date: Wed, 27 Mar 2024 19:00:02 -0400

<!--X-Head-of-Message-End-->
<!--X-Head-Body-Sep-Begin-->

<!--X-Head-Body-Sep-End-->
<!--X-Body-of-Message-->
On Wed, Mar 27, 2024 at 10:30:41PM +0100, Jakub Wilk wrote:
While looking through upstream git for a fix for this¹, I stumbled upon
another write(1)/wall(1) control character injection vulnerability,
introduced last year in util-linux v2.39.

The offending commits are:

* https://github.com/util-linux/util-linux/commit/8a7b8456d1dc0e7c
  ("write: correctly handle wide characters")
* https://github.com/util-linux/util-linux/commit/aa13246a1bf1be9e
  ("wall: use fputs_careful()")

The added comment says:

The locale of the recipient is nominally unknown,
but it's a solid bet that the encoding is compatible with the author's.

Alas the bet is not that solid when writer's locale encoding is controlled
by an attacker.

We can exploit this against terminal emulators that recognize C1 control
characters, such as Linux VTs or screen(1):

   $ printf '\302\23331mMOO\302\2330m\n' | LC_ALL=kk_KZ wall

I don't see any good way to fix this on the util-linux's side. It should be
fixed on the terminal emulators' side by disabling C1 support.

¹ https://github.com/util-linux/util-linux/commit/404b0781f52f7c04
  ("wall: fix escape sequence Injection [CVE-2024-28085]")

Would enforcing UTF-8 validity (regardless of user locale) be a
solution?
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
Attachment:
signature.asc
Description: 

<!--X-Body-of-Message-End-->
<!--X-MsgBody-End-->
<!--X-Follow-Ups-->

<!--X-Follow-Ups-End-->
<!--X-References-->
<!--X-References-End-->
<!--X-BotPNI-->

By Date

By Thread

Current thread:

CVE-2024-28085: Escape sequence injection in util-linux wall Skyler Ferrante (RIT Student) (Mar 27)

Re: CVE-2024-28085: Escape sequence injection in util-linux wall nightmare . yeah27 (Mar 27)

Re: CVE-2024-28085: Escape sequence injection in util-linux wall Jakub Wilk (Mar 27)

Re: CVE-2024-28085: Escape sequence injection in util-linux wall Demi Marie Obenour (Mar 27)

Re: CVE-2024-28085: Escape sequence injection in util-linux wall Solar Designer (Mar 27)

<!--X-BotPNI-End-->
<!--X-User-Footer-->
<!--X-User-Footer-End-->