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

Open Source and information security mailing list archives

Date: Fri, 04 Feb 2022 19:29:46 +0300
From: Askar Safin via Fulldisclosure
 <fulldisclosure@...lists.org>
To: fulldisclosure@...lists.org
Subject: [FD] getenv("=A") works (no particular vulnerability)

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/

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives