The Hardened PHP project has
recently announced its existence; naturally, a Gentoo
package is already available. The PHP language is highly popular for
the creation of web applications, but it has long suffered from a
reputation for poor security. This reputation is perhaps not entirely
fair; the number of sites which have actually been compromised as a result
of PHP vulnerabilities is small. Nonetheless, PHP has tended to have more
holes than it really should, given its wide deployment.
Hardened PHP is attempting to address that
problem by adding patches to the language implementation which close off a
number of potential security problems.
Those interested in the actual changes being made can learn more on
this page. These changes include:
The addition of "canaries" to the internal memory manager. PHP uses a
variant of malloc() which tracks all allocated memory, making
it easy to reclaim everything after the completion of a web request. The
Hardened PHP patch adds special, random values at the beginning and
end of each allocated block and checks to see whether those values
have been overwritten when the memory is freed. These checks should
help defend against bugs in the PHP system which allow heap overflow
attacks.
Canaries are also added to PHP's internal linked list structures.
The "%n" format specifier has been removed from (some of)
PHP's internal string printing functions in an attempt to head off
certain types of format string attacks.
The PHP include directive has some additional restrictions
which prevent the inclusion of program text from remote sources.
Checks are made for strings with embedded NULL characters.
This effort is worthy and worthwhile, but it is also inadequate for a
couple of reasons. Exploitable buffer overflows in PHP are relatively
rare; instead, PHP programs tend to suffer from different classes of
vulnerabilities, such as cross-site scripting, SQL injection, and command
injection. A truly hardened PHP would attempt to address these problems
through tighter restrictions on what scripts can do and enforced checking
of input strings.
The fact that there needs to be a "hardened PHP" project in the first place
is also a bad sign, unless this project is simply a staging area for
patches on their way into the mainline. PHP is used to implement an
unbelievable number of web sites; any vulnerabilities in PHP put vast
numbers of systems at risk. Security should be at the top of the PHP
project's goals; every PHP installation should be hardened. The
Hardened PHP project is a good thing; lets hope its work is quickly picked
up by the main PHP distribution.
CVS (through version 1.11.15 or 1.12.7) contains a remotely exploitable heap overflow vulnerability; see this advisory from Stefan Esser for details. If you are running cvs with the "pserver" protocol, a quick upgrade is recommended (dropping pserver is also a very good idea for security-conscious sites).
Evgeny Demidov discovered a potential buffer overflow in a Kerberos 4
component of heimdal, a free implementation of Kerberos 5. The
problem is present in kadmind, a server for administrative access to
the Kerberos database. This problem could perhaps be exploited to
cause the daemon to read a negative amount of data which could lead to
unexpected behavior.
The icecast server has a read error in its authorization code which can enable a denial of service attack; upgrading to version 2.0.1 fixes the problem.
iDEFENSE identified a vulnerability in the Opera Web Browser that could
allow remote attackers to create or truncate arbitrary files. The KDE team
has found that similar vulnerabilities exists in all version of KDE, up to
KDE 3.2.2 inclusive. See this advisory for
more information.
There is an integer overflow in the SCTP code in the Linux kernel starting
with 2.4.23-pre5 and up to and including 2.4.25. This could allow for a
local root exploit. See this
advisory for more details.
Steve Grubb discovered a number of problems in the libuser library that
can lead to a crash in applications linked to it, or possibly write 4GB
of garbage to the disk.
A problem has been discovered in mah-jong, a variant of the original
Mah-Jong game, that can be utilized to crash the game server after
dereferencing a NULL pointer. This bug be exploited by any client
that connects to the mah-jong server.
The neon library (through version 0.24.5) contains a buffer overflow in its date parsing code, allowing arbitrary code execution when connecting to a hostile server. See this advisory for details. This vulnerability also affects related applications (such as cadaver).
Versions of the subversion source management package up to and including 1.0.2 suffer from a remotely exploitable buffer overflow vulnerability in their date parsing code; see this advisory for details. "Exploiting this vulnerability on not heavily protected servers is trivial
even for beginners, therefore it is strongly recommended to update
immediately."
A memory leak has been discovered in mod_ssl that may be triggered by
sending normal HTTP requests to the Apache HTTPS port. An attacker can
exploit this vulnerability to consume all memory available in the server,
thus causing a denial of service condition. This problem has been fixed in
Apache 2.0.49.
Versions of apache 1 through 1.3.30 include several minor vulnerabilities, including the writing of unescaped data to the error log file, a denial of service vulnerability, and a parsing failure in Allow/Deny rules on big-endian, 64-bit platforms. See the apache 1.3.31 announcement for details.
Versions of clamav prior to 0.70 fail to check filenames when responding to viruses; with certain configurations, this failure can allow an attacker to execute arbitrary commands.
The cvs client is vulnerable to a pathname vulnerability which can allow a hostile server to overwrite files on the local system. The cvs server is subject to a similar vulnerability which allows the checkout of RCS archives anywhere on the server system. Versions 1.11.15 and 1.12.7 fix the problem.
Georgi Guninski discovered two stack-based buffer overflows.
CAN-2004-0399: When "sender_verify = true" is configured in exim.conf a
buffer overflow can happen during verification of the sender. This problem
is fixed in exim 4.
CAN-2004-0400: When headers_check_syntax is configured in exim.conf a
buffer overflow can happen during the header check. This problem does also
exist in exim 4.
"fam" (file alteration monitor) watches files and directories for changes and lets interested applications know when something happens. This package has a flaw in its group handling that blocks some legitimate operations while, at the same time, exposing the names of files that should otherwise be invisible.
GtkHTML is the HTML rendering widget used by the Evolution mail reader.
GtkHTML supplied with versions of Evolution prior to 1.2.4 contain a bug
when handling HTML messages. Alan Cox discovered that certain malformed
messages could cause the Evolution mail component to crash.
Versions of ipsec-tools prior to 0.2.5 contain a vulnerability wherein the racoon utility fails to verify digital signatures on some packets. This hole can lead to unauthorized connections or man-in-the-middle attacks. See this advisory for details.
racoon does not check the length of ISAKMP headers. Attackers may be able
to craft an ISAKMP header of sufficient length to consume all available
system resources, causing a Denial of Service. This advisory contains additional
details.
kdelibs (and, thus, Konqueror) has a vulnerability where a hostile server can force the disclosure of cookies that should not be presented to it. KDE versions 3.1.3 and later contain a fix.
KDE has issued a security advisory for all
versions of kdepim as distributed with KDE versions 3.1.0 through 3.1.4
inclusive. A carefully crafted .VCF file potentially enables local
attackers to compromise the privacy of a victim's data or execute arbitrary
commands with the victim's privileges. The Common Vulnerabilities and
Exposures project (cve.mitre.org) has assigned the name CAN-2003-0988 to
this issue.
The 2.4 and 2.6 kernels contain a
vulnerability in the iso9660 (CDROM) filesystem which can be used by a
local attacker to obtain root privileges. The exploit requires creating a
specially-crafted filesystem and getting the kernel to mount it. Many
systems are configured to automatically mount CDs on insertion, however, so
the possibility of this vulnerability being exploited by users with
physical access to the system is real. The 2.4.26 kernel contains the fix,
which will also be merged into the upcoming 2.6.6 release.
A locally exploitable integer overflow has been found the multicast code
of the Linux kernel versions 2.4.22 to 2.4.25 and 2.6.1 - 2.6.3. A
successful exploit could lead to full superuser privileges.
The kernel-utils package contains several utilities that can be used to
control the kernel or machine hardware. In Red Hat Linux 8.0 this package
contains user mode linux (UML) utilities.
The uml_net utility in kernel-utils packages with Red Hat Linux 8.0 was
incorrectly shipped setuid root. This could allow local users to control
certain network interfaces, add and remove arp entries and routes, and put
interfaces in and out of promiscuous mode.
All users of the kernel-utils package should update to these packages that
contain a version of uml_net that is not setuid root.
Alternatively, as a work-around to this vulnerability issue the following
command as root:
LHA is an archiving and compression utility for LHarc format archives. Ulf
Harnhammar discovered two stack buffer overflows and two directory
traversal flaws in LHA. See this advisory+patch for more details.
CAN-2004-0234: An attacker could exploit the buffer overflows by creating a
carefully crafted LHA archive in such a way that arbitrary code would be
executed when the archive is tested or extracted by a victim.
CAN-2004-0235: An attacker could exploit the directory traversal issues to
create files as the victim outside of the expected directory.
Glenn Randers-Pehrson discovered a problem in connection with 16-bit
samples from libpng, an interface for reading and writing PNG
(Portable Network Graphics) format files. The starting offsets for
the loops are calculated incorrectly which causes a buffer overrun
beyond the beginning of the row buffer.
Yuuichi Teranishi discovered a flaw in libxml2 versions prior to 2.6.6.
When fetching a remote resource via FTP or HTTP, libxml2 uses special
parsing routines. These routines can overflow a buffer if passed a very
long URL. If an attacker is able to find an application using libxml2 that
parses remote resources and allows them to influence the URL, then this
flaw could be used to execute arbitrary code.
Matthew Galgoci of Red Hat discovered a Denial of Service (DoS)
vulnerability in versions of Mailman prior to 2.1. An attacker could send
a carefully-crafted message causing mailman to crash. The Common
Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name
CAN-2003-0991 to this issue.
Apache's mod_python module could crash the httpd process if a specific,
malformed query string was sent.
The Apache Foundation has reported that mod_python may be prone to
Denial of Service attacks when handling a malformed query. Mod_python
2.7.9 was released to fix the vulnerability, however, because the
vulnerability has not been fully fixed, version 2.7.10 has been released.
Users of mod_python 3.0.4 are not affected by this vulnerability.
Mozilla 1.4 contains a few vulnerabilities, including disclosure of cookies to the wrong server, a scripting vulnerability which can allow an attacker to run arbitrary code, and an S/MIME vulnerability which can lead to remote denial of service or code execution attacks.
A vulnerability was discovered in mpg321, a command-line mp3 player,
whereby user-supplied strings were passed to printf(3) unsafely. This
vulnerability could be exploited by a remote attacker to overwrite
memory, and possibly execute arbitrary code. In order for this
vulnerability to be exploited, mpg321 would need to play a malicious
mp3 file (including via HTTP streaming).
The neon WebDAV library contains format string vulnerabilities which may be exploited by a hostile DAV server. This vulnerability exists in utilities which use neon, including cadaver and OpenOffice.org.
Some some vulnerabilities exsist in the Nessus NASL scripting engine. To
exploit these flaws, an attacker would need to have a valid Nessus account
as well as the ability to upload arbitrary Nessus plugins in the Nessus
server (this option is disabled by default) or he/she would need to trick a
user somehow into running a specially crafted nasl script. Read the full
advisory for additional information.
netpbm is graphics conversion toolkit made up of a large number of
single-purpose programs. Many of these programs were found to create
temporary files in an insecure manner, which could allow a local
attacker to overwrite files with the privileges of the user invoking a
vulnerable netpbm tool.
From the advisory:
"During a pen-test we stumbled across a nasty bug in OpenSSH-portable
with PAM support enabled (via the --with-pam configure script switch). This
bug allows a remote attacker to identify valid users on vulnerable systems,
through a simple timing attack. The vulnerability is easy to exploit and
may have high severity, if combined with poor password policies and other
security problems that allow local privilege escalation."
Steve Grubb found some problems in the passwd program. Passwords given to
passwd via stdin are one character shorter than they are supposed to be.
He also discovered that pam may not have been sufficiently initialized to
ensure safe and proper operation. A few small memory leaks have been fixed
as well.
The postfix MTA, versions through 1.1.12 (but not 2.0) is subject to two remotely exploitable denial of service vulnerabilities; see this advisory from Michal Zalewski for details.
A portability workaround was applied in version 1.2.9 of the FTP server ProFTPD. As a side-effect, CIDR based
(aaa.bbb.ccc.ddd/NN) ACL entries in "Allow" and "Deny" directives act like
an "AllowAll" directive and so FTP clients are granted access to files and
directories although the server configuration might explicitly deny this.
See this bug
report.
See the rsync homepage for the
April 2004
advisory: "There is a security problem in all versions prior to
2.6.1 that affects only people running a read/write daemon WITHOUT using
chroot. If the user privs that such an rsync daemon is using is anything
above "nobody", you are at risk of someone crafting an attack that could
write a file outside of the module's "path" setting (where all its files
should be stored). Please either enable chroot or upgrade to 2.6.1. People
not running a daemon, running a read-only daemon, or running a chrooted
daemon are totally unaffected."
The SUSE 9.1 live CD boots with ssh connections enabled and no root password; as a result, a remote attacker can gain privileged access simply by logging in as root.
The tar utility does not properly filter file names containing
"../", meaning that a hostile archive can, if unpacked by an
unsuspecting user, overwrite any file that is writable by that user. GNU
tar versions 1.13.19 and earlier are vulnerable; unzip through version 5.42
has the same vulnerability.
TCPDUMP v3.8.1 and earlier versions contain multiple flaws in the packet
display functions for the ISAKMP protocol. Upon receiving specially
crafted ISAKMP packets, TCPDUMP will try to read beyond the end of the
packet capture buffer and crash. More information is available in this Rapid7 advisory.
This vulnerability,
originally thought to be confined to BSD-derived systems, was first covered
in the July 26th Security
Summary. It is now known that Linux telnet daemons are vulnerable as
well.
Steve Grubb discovered two potential issues in the utempter program:
If the path to the device contained /../ or /./ or //, the program
was not exiting as it should. It would be possible to use something like
/dev/../tmp/tty0, and then if /tmp/tty0 were deleted and symlinked to
another important file, programs that have root privileges that do no
further validation can then overwrite whatever the symlink pointed to.
Several calls to strncpy without a manual termination of the string.
This would most likely crash utempter.
XChat is vulnerable to a stack overflow that may allow a remote attacker to
run arbitrary code. The SOCKS 5 proxy code in XChat is vulnerable to a
remote exploit. Users would have to be using XChat through a SOCKS 5
server, enable SOCKS 5 traversal which is disabled by default and also
connect to an attacker's custom proxy server. This vulnerability may allow
an attacker to run arbitrary code within the context of the user ID of the
XChat client.
A vulnerability exists in xine-lib where playing a specially crafted Real
RTSP stream could run malicious code as the user playing the stream. More
details can be found in this
advisory. The problem has been fixed in xine-lib 1-rc4.
Shaun Colley discovered a problem in xine-ui, the xine video player
user interface. A script contained in the package to possibly remedy
a problem or report a bug does not create temporary files in a secure
fashion. This could allow a local attacker to overwrite files with
the privileges of the user invoking xine.
Bruce Schneier's CRYPTO-GRAM newsletter for May is out. Topics this month
include warrants as a security measure, airport security, security
consumers, and more. "Being a smart security consumer is hard, just as being a good citizen
is hard.... We need to become informed. Otherwise it's no different
than walking into a car dealership without knowing anything about the
different models and prices -- we're going to get ripped off."
The Detection of Intrusions and Malware & Vulnerability Assessment conference is happening July 6 and 7 in Dortmund, Germany. Registration is now open; click below for the details.
