#45132 [Asn]: escapeshellcmd removes swedish characters
ID: 45132
Updated by: jani@php.net
Reported By: tom at collegit dot se
Status: Assigned
Bug Type: Strings related
-Operating System: Linux www2 2.6.24.7-grsec
+Operating System: *
-PHP Version: 5.2.6
+PHP Version: 5.*, 6CVS (2009-05-05)
Assigned To: iliaa
New Comment:
See also bug #44564 (and can still verify using latest CVS)
Previous Comments:
------------------------------------------------------------------------
[2008-08-07 06:23:19] tstarling at wikimedia dot org
The issue is that previously 8-bit clean locales, like "C", are now
being validated for whatever character set they supposedly are, with
characters above 127 being removed.
The suggested fix, here and on
https://bugzilla.wikimedia.org/show_bug.cgi?id=14944
, appears to reopen
whatever security vulnerability it was that the patch fixed in the first
place.
$ LANG=C php eval.php
> setlocale(LC_CTYPE, 'en_US.UTF-8')
> echo escapeshellarg("\xC3\x96")
'Ö'
> passthru('locale')
LANG=C
LC_CTYPE="C"
LC_NUMERIC="C"
LC_TIME="C"
LC_COLLATE="C"
LC_MONETARY="C"
LC_MESSAGES="C"
LC_PAPER="C"
LC_NAME="C"
LC_ADDRESS="C"
LC_TELEPHONE="C"
LC_MEASUREMENT="C"
LC_IDENTIFICATION="C"
LC_ALL=
Because the environment variable LC_CTYPE is not set by setlocale(),
the spawned shell sees the old character set, not the new one. So the
shell can be passed an argument escaped for the wrong character set,
potentially opening a vulnerability.
I'm assuming that the attack scenario for this vulnerability is where
an attacker can set environment variables such as LANG to a vulnerable
character set, before starting PHP. Because if an attacker can set
environment variables during execution of a script, the bug is not
fixed. But in that case you're probably screwed anyway.
------------------------------------------------------------------------
[2008-05-29 23:09:34] felipe@php.net
Try using:
setlocale(LC_CTYPE, "UTF8", "en_US.UTF-8");
------------------------------------------------------------------------
[2008-05-29 22:55:58] jani@php.net
Ilia, did that fix get into actual release..?
------------------------------------------------------------------------
[2008-05-29 22:53:54] tom at collegit dot se
Description:
------------
Since my web server got updated to 5.2.6 escapeshellcmd() has started
removing all Swedish characters from user input. Looks a lot like bug
#44564.
'./configure' '--with-apxs2=/usr/local/apache/bin/apxs' '--with-
mysql=/usr/local/mysql' '--enable-debug=no' '--enable-track-vars' '--
with-imap=/usr/local/imap' '--with-mcrypt' '--with-mhash'
'--with-dom'
'--with-gd' '--with-jpeg-dir' '--enable-ftp' '--with-freetype-
dir=/usr' '--with-zlib-dir=/usr' '--with-png-dir=/usr' '--enable-
dbase' '--with-gettext' '--with-zlib'
'--enable-inline-optimization'
'--with-openssl' '--with-curl' '--with-curlwrappers'
'--enable-exif'
'--with-imap-ssl' '--enable-bcmath' '--enable-mbstring'
'--enable-
wddx' '--with-xsl' '--with-pdo-mysql=/usr/local/mysql' '--with-
mysqli=/usr/local/mysql/bin/mysql_config' '--enable-soap' '--enable-
sockets' '--with-mssql' '--with-ming' '--with-pspell'
'--enable-
calendar' '--enable-bcmath' '--with-t1lib' '--with-
pgsql=/usr/local/pgsql' '--with-tidy' '--enable-zip'
Reproduce code:
---------------
$test = "åäö";
$test = (escapeshellcmd($test));
print $test;
Expected result:
----------------
"åäö"
Actual result:
--------------
""
------------------------------------------------------------------------
--
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