There has been a surprising series of kernel security problems reported
over the last week. These include:
The uselib() vulnerability disclosed
by Paul Starzetz. A locking mistake in an old and mostly unused
system call creates a race condition which can be exploited to change
protections on memory - and compromise the system. The exploit has
not been released, but Mr. Starzetz claims that the race is relatively
easy to exploit by first consuming large amounts of memory to force
the kernel to sleep in the right spot.
Paul Starzetz also discovered a race
condition in the page fault handler which can only be exploited on
SMP systems. If two threads tried to expand the same downward-growing
memory segment at the same time, the result could be an exploitable
corruption of the page tables.
The grsecurity team, frustrated at a seeming lack of interest in
security problems among the kernel developers, disclosed five vulnerabilities at once.
One of these is a denial-of-service problem where users could lock
more than the authorized amount of memory into physical RAM; as it
turns out, the kernel developers still are
not overly concerned about that problem. The other
vulnerabilities require root access (or at least access to physical
devices) to exploit; one of them is in a driver which does not compile
in 2.6.
Fixes for the first two vulnerabilities have been merged into the
pre-2.6.11 BitKeeper repository; the last set will be fixed as well, but
with less urgency. Fixes can also be found in the -ac tree and in the updated kernels being
issued by distributors.
One concern that has been raised by these disclosures is that the new
kernel development model, by encouraging such large changes between
releases, is allowing the creation of more security problems. While that
worry could yet prove to be justified, all of the vulnerabilities listed
above, with the exception of the RLIMIT_MEMLOCK denial of service
problem, are present in the 2.4 kernel as well. They were not introduced
or enabled by the new development model.
Another concern is more valid, however: the kernel development project does
not have an official security contact or process for handling security
problems. Developers who know how the kernel process works have no trouble
getting consideration for security-related problems and patches, but the
whole process looks far more opaque to the rest of the world. There is a
clear need for an easily-found contact for kernel security issues. Chris
Wright, who has done a fair amount of security-related kernel work, is pushing for improvements in this area, and,
most importantly, has volunteered to do much of the work. So chances are
this problem will not last much longer.
Peter Samuelson, upstream maintainer of bmv, a PostScript viewer for
SVGAlib, discovered that temporary files are created in an insecure
fashion. A malicious local user could cause arbitrary files to be
overwritten by a symlink attack.
Gentoo Linux developer Tavis Ormandy found a format string bug in Dillo's
handling of messages in a_Interface_msg(). An attacker could craft a
malicious web page which, when accessed using Dillo, would trigger the
format string vulnerability and potentially execute arbitrary code with the
rights of the user running Dillo.
Patrice Fournier discovered a vulnerability in the authorization
subsystem of hylafax, a flexible client/server fax system. A local or
remote user guessing the contents of the hosts.hfaxd database could
gain unauthorized access to the fax system. Fixed in HylaFAX
4.2.1.
Thiago Macieira discovered a vulnerability in the kioslave library,
which is part of kdelibs, which allows a remote attacker to execute
arbitrary FTP commands via an ftp:// URL that contains an URL-encoded
newline before the FTP command.
Paul Starzetz discovered a race condition in the ELF library and a.out
binary format loaders, which can be locally exploited in several
different ways to gain root privileges. (CAN-2004-1235)
Liang Bin found a design flaw in the capability module. After this
module was loaded on demand in a running system, all unprivileged user
space processes got all kernel capabilities (thus essentially root
privileges). (CAN-2004-1337)
According to this KDE
Security Advisory, two flaws in the Konqueror web browser make it
possible to by pass the sandbox environment which is used to run
Java-applets. All versions of KDE up to KDE 3.3.1 inclusive are affected.
KDE 3.3.2 is not affected.
Jeroen van Wolffelaar discovered a problem in lintian, the Debian
package checker. The program removes the working directory even if it
wasn't created at program start, removing an unrelated file or
directory a malicious user inserted via a symlink attack.
Florian Weimer discovered a cross-site scripting vulnerability in
mailman's automatically generated error messages. An attacker could
craft an URL containing JavaScript (or other content embedded into
HTML) which triggered a mailman error page. When an unsuspecting user
followed this URL, the malicious content was copied unmodified to the
error page and executed in the context of this page.
The namazu2 full text search engine has a cross-site scripting vulnerability
that may allow an attacker to display arbitrarily crafted text
by the use of specially crafted input information.
Arjan van de Ven discovered a buffer overflow in rquotad on 64bit
architectures; an improper integer conversion could lead to a buffer
overflow. An attacker with access to an NFS share could send a specially
crafted request which could then lead to the execution of arbitrary code.
Gentoo Linux developer Marcus Hanwell discovered that poppassd_pam did
not check that the old password was valid before changing passwords.
Subsequent investigation revealed that poppassd_pam did not call
pam_authenticate before calling pam_chauthtok.
TikiWiki lacks a check on uploaded images in the Wiki edit page. A
malicious user could run arbitrary commands on the server by uploading and
calling a PHP script.
An unchecked strcat() in unrtf may overflow the bounds of a static buffer.
Using a specially crafted file, possibly delivered by e-mail or over the
web, an attacker may execute arbitrary code with the permissions of the
user running UnRTF.
The GNU a2ps utility fails to properly sanitize filenames, which can be
abused by a malicious user to execute arbitrary commands with the
privileges of the user running the vulnerable application. More
information at Security
Focus.
cyrus-sasl has a vulnerability involving a buffer overflow
in the digestmda5.c file. A remote attacker may be able
to compromise the system. Also, a local user may be able to
exploit a vulnerability by using the SASL_PATH environment
variable.
"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.
There is a vulnerability in the foomatic-filters package. This
vulnerability is due to insufficient checking of command-line parameters
and environment variables in the foomatic-rip filter. This vulnerability
may allow both local and remote attackers to execute arbitrary commands on
the print server with the permissions of the spooler.
A buffer overflow in the MSN protocol handler for gaim 0.79 to 1.0.1 allows
remote attackers to cause a denial of service (application crash) and
possibly execute arbitrary code via an "unexpected sequence of MSNSLP
messages" that results in an unbounded copy operation that writes to the
wrong buffer.
Jim Paris has discovered a cross-site scripting vulnerability in
Gallery. By sending a carefully crafted URL, an attacker can inject and
execute script code in the victim's browser window, and potentially
compromise the users gallery.
The gdk-pixbuf and gtk2 libraries contain vulnerabilities in their handling of BMP and XPM files which can lead to denial of service and, potentially, code execution attacks.
gettext insecurely creates temporary files in world-writeable directories
with predictable names. A local attacker could create symbolic links in
the temporary files directory, pointing to a valid file somewhere on the
filesystem. When gettext is called, this would result in file access with
the rights of the user running the utility, which could be the root user.
Silvio Cesare discovered a potential information leak in glibc. It allows
LD_DEBUG on SUID binaries where it should not be allowed. This has various
security implications, which may be used to gain confidential information.
An attacker can gain the list of symbols a SUID application uses and their
locations and can then use a trojaned library taking precedence over those
symbols to gain information or perform further exploitation.
The catchsegv script in the glibc package has a symlink vulnerability
that may allow a local user to overwrite arbitrary
files with the permissions of the user that is running the script.
Several scripts packaged with gnome-vfs, using its "extfs" capability, have security flaws. These scripts tend not to be used on many systems, but their presence can still be a threat.
Javier Fernández-Sanguino Peña discovered that the auxiliary scripts
"eqn2graph" and "pic2graph" created temporary files in an insecure
way, which allowed exploitation of a race condition to create or
overwrite files with the privileges of the user invoking the program.
Recently, Trustix Secure Linux discovered a vulnerability in the groff
package. The utility "groffer" created a temporary directory in an
insecure way, which allowed exploitation of a race condition to create
or overwrite files with the privileges of the user invoking the
program.
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.
Javier Fernández-Sanguino Peña has discovered multiple insecure uses
of temporary files that could lead to overwriting arbitrary files via
a symlink attack.
Pavel Kankovsky discovered that several overflows found in the libXpm
library also applied to imlib. He also fixed a number of other potential
flaws. A remote attacker could entice a user to view a carefully-crafted
image file, which would potentially lead to execution of arbitrary code
with the rights of the user viewing the image. This affects any program
that makes use of the imlib library.
Faheem Mitha noticed that the iptables command, an administration tool for
IPv4 packet filtering and NAT, did not always load the required modules on
its own as it was supposed to. This could lead to firewall rules not being
loaded on system startup. This caused a failure in connection with rules
provided by lokkit at least.
The Konqueror browser (via kdelibs) contains a vulnerability which can cause it to send email without the user's interaction or consent. See this bug report for details.
There is a buffer overflow in the password history handling code of
libkadm5srv which could be exploited by an authenticated user to execute
arbitrary code on a Key Distribution Center (KDC) server.
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:
Several buffer overflows have been discovered in libgd's PNG handling
functions.
If an attacker tricked a user into loading a malicious PNG image, they
could leverage this into executing arbitrary code in the context of
the user opening image. Most importantly, this library is commonly
used in PHP. One possible target would be a PHP driven photo website
that lets users upload images. Therefore this vulnerability might lead
to privilege escalation to a web server's privileges.
Multiple buffer overflows in the gd graphics library (libgd) 2.0.21 and
earlier may allow remote attackers to execute arbitrary code via malformed
image files that trigger the overflows due to improper calls to the
gdMalloc function.
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.
libxml2 prior to version 2.6.14 has multiple buffer overflow
vulnerabilities, if a local user passes a specially crafted
FTP URL, arbitrary code may be executed.
Stephen Dranger discovered that LinPopUp contains a buffer overflow in
string.c, triggered when replying to a remote user message. A remote
attacker could craft a malicious message that, when replied to using
LinPopUp, would exploit the buffer overflow. This would result in the
execution of arbitrary code with the privileges of the user running
LinPopUp.
Trustix Secure Linux discovered a vulnerability in a supplemental script of
the lvm10 package. The program "lvmcreate_initrd" created a temporary
directory in an insecure way, which could allow a symlink attack to create
or overwrite arbitrary files with the privileges of the user invoking the
program.
Several vulnerabilities exist in the Mozilla web browser and derived
products, the most serious of which could allow a remote attacker to
execute arbitrary code on an affected system. See the CERT advisory for details.
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).
Several problems have been discovered in MySQL. Oleksandr Byelkin noticed
that ALTER TABLE ... RENAME checks CREATE/INSERT rights of the old table
instead of the new one. (CAN-2004-0835) Lukasz Wojtow noticed a buffer
overrun in the mysql_real_connect function. (CAN-2004-0836) Dean Ellis
noticed that multiple threads ALTERing the same (or different) MERGE tables
to change the UNION can cause the server to crash or stall. (CAN-2004-0837)
Jonathan Rockway discovered that NASM-0.98.38 has an unprotected
vsprintf() to an array in preproc.c. This code vulnerability may lead
to a buffer overflow and potential execution of arbitrary code.
Michal Zalewski discovered a bug in the netkit-telnet server (telnetd)
whereby a remote attacker could cause the telnetd process to free an
invalid pointer. This causes the telnet server process to crash, leading
to a straightforward denial of service (inetd will disable the service if
telnetd is crashed repeatedly), or possibly the execution of arbitrary code
with the privileges of the telnetd process (by default, the 'telnetd'
user).
The der_chop script in openssl has a temp file vulnerability that may allow
an attacker to overwrite arbitrary files with the permissions that
the script is running under.
A race condition and possible information leak has been discovered in
Perl's File::Path::rmtree(). This function changes the permission of files
and directories before removing them to avoid problems with wrong
permissions. However, they were made readable and writable not only for the
owner, but for the entire world, which opened a race condition and a
possible information leak (if the actual removal of a file/directory failed
for some reason).
Stefan Esser has issued an advisory regarding a
remotely exploitable hole in PHP (through version 4.3.7). If the
memory_limit feature is in use (as it should be, to prevent denial
of service attacks), allocation failures can be forced at highly
inopportune times, and those failures can be exploited to execute arbitrary
code. The exploit is described as "quite easy," and it can be done
regardless of whether Apache1 or Apache2 is in use. Upgrading to PHP 4.3.8 fixes the
problem; yesterday's PHP 5.0 release also contains the fix (but the
final release candidate did not).
PHP has an out of bounds memory write access vulnerability and
an integer overflow/underflow problem. See the PHP 4.3.10 Release Announcement for details.
ProZilla contains several exploitable buffer overflows in the code handling
the network protocols. A remote attacker could setup a malicious server
and entice a user to retrieve files from that server using ProZilla. This
could lead to the execution of arbitrary code with the rights of the user
running ProZilla.
Max Vozeler discovered a vulnerability in pppoe, the PPP over Ethernet
driver from Roaring Penguin. When the program is running setuid root
(which is not the case in a default Debian installation), an attacker
could overwrite any file on the file system.
The upstream developers of Ruby have corrected a problem in the CGI
module for this language. Specially crafted requests could cause an
infinite loop and thus cause the program to eat up cpu cycles.
sharutils contains two buffer overflows. Ulf Harnhammar discovered a buffer
overflow in shar.c, where the length of data returned by the wc command is
not checked. Florian Schilhabel discovered another buffer overflow in
unshar.c. An attacker could exploit these vulnerabilities to execute
arbitrary code as the user running one of the sharutils programs.
SpamAssassin contains an unspecified Denial of Service vulnerability. By
sending a specially crafted message an attacker could cause a Denial of
Service attack against the SpamAssassin service.
Subversion has a remote Denial of Service vulnerability
that may allow a server that runs svnserve to execute
arbitrary code. See this advisory for more information.
Versions of sudo prior to 1.6.8p2 fail to properly sanitize the environment prior to running shell scripts; this failure can be exploited by a sudo user to subvert scripts and obtain shell access. See the 1.6.8p2 announcement for more information.
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.
The tiff library contains several buffer overflows which may be exploited
by way of maliciously-crafted image files. See this advisory for more information.
The unarj uncompression utility has a buffer overflow vulnerability
from handling long file names in an archive. An attacker can
cause unarj to crash or execute arbitrary code.
A new set of modeline-related vulnerabilities has been discovered in versions of vim prior to 6.3-r2. These vulnerabilities could conceivably be exploited by a local user to obtain the privileges of another user.
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.
Several buffer overflows have been discovered in xine-lib, the video/audio
codec library for Xine frontends (xine-ui, totem-xine, kaffeine, and
others). If an attacker tricked a user into loading a malicious RTSP stream
or a stream with specially crafted AIFF audio or PNM image data, they could
exploit this to execute arbitrary code with the privileges of the user
opening the audio/video file. See this advisory
for more information.
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.
xpdf has a
potential buffer overflow problem caused by insufficient input validation.
A specially crafted PDF file can allow an
attacker to execute code with privileges of the xpdf user.
Several xpdf integer overflow vulnerabilities can be exploited via a
mal-formed PDF document. Similar vulnerabilities can be found in kpdf and
in cupsys which share code. Additional information can be found in this KDE security advisory.
Luke "infamous41md" discovered multiple vulnerabilities in xzgv, a picture
viewer for X11 with a thumbnail-based selector. Remote exploitation of an
integer overflow vulnerability could allow the execution of arbitrary
code.
HexView discovered a buffer overflow in the zip package. The overflow is
triggered by creating a ZIP archive of files with very long path
names. This vulnerability might result in execution of arbitrary code with
the privileges of the user who calls zip. This flaw may lead to privilege
escalation on systems which automatically create ZIP archives of user
supplied files, like backup systems or web applications.
