full-disclosure - Re: [FD] getenv("=A") works (no particular vulnerability)

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Message-ID: <CACV6rWKwArWRmmFE7pZjcYr86_3rWkumR1pqYUf3bU=omydDNA@mail.gmail.com>
Date: Fri, 4 Feb 2022 14:41:25 -0600
From: Andy Bach <afbach@...il.com>
To: Askar Safin <safinaskar@...l.ru>
Cc: fulldisclosure@...lists.org
Subject: Re: [FD] getenv("=A") works (no particular vulnerability)

bash, for one, doesn't allow = to start an env var name

On Fri, Feb 4, 2022 at 2:25 PM Askar Safin via Fulldisclosure <
fulldisclosure@...lists.org> wrote:

> TL;DR: this mail doesn't contain any actual vulnerability, just an idea.
>
> Consider this C code for Linux and glibc:
>
> ---------
> #define _GNU_SOURCE 1
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> char *new_env[] = {"=A=B", 0};
> int
> main ()
> {
>   environ = new_env;
>   printf("%s\n", getenv("=A")); // prints "B"
>   return 0;
> }
> ---------
>
> This code prints "B". I. e. glibc allows variables starting with "=". It
> is quite possible such behavior can lead to various vulnerabilities.
>
> It is possible this list is inappropriate for such message. If so, please,
> say, where I should post such message next time.
>
> ==
> Askar Safin
> http://safinaskar.com
> https://sr.ht/~safinaskar
> https://github.com/safinaskar
>
> _______________________________________________
> Sent through the Full Disclosure mailing list
> https://nmap.org/mailman/listinfo/fulldisclosure
> Web Archives & RSS: http://seclists.org/fulldisclosure/
>

-- 

a

Andy Bach,
afbach@...il.com
608 658-1890 cell
608 261-5738 wk

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