Making sweeping statements about the security of a particular program
can come back to haunt you rather quickly as the recent case of a local
root exploit in cdrecord demonstrates. During a discussion of recent changes
in the 2.6 Linux kernel (as covered
by LWN), Jörg Schilling, the author of cdrecord, made a comment about
the security of that program:
Judging from the number of reports, I would guess that the Linux kernel is
much more insecure than cdrecord.
That statement could well be true, but in making it, Jörg may have
inspired someone to take a closer look at cdrecord.
Max Vozeler recently found that cdrecord fails to drop privileges when it executes
an external program, and that users can specify which external program is run
via the RSH environment variable. If cdrecord is
installed setuid root, any local user can exploit this vulnerability to
gain root access; multiple exploits have already been posted on bugtraq.
Jörg recommends installing
cdrecord as a setuid root.
cdrecord uses the elevated privileges to lock its buffers into physical
memory and to request real-time scheduling, both of which reduce the
chances of a buffer underrun. In addition, cdrecord opens the
SCSI device before dropping privileges back to that of the user who executed
it. In the case of a remote device, it executes the command to access
that device, but prior to this bug being fixed, it did that with
elevated privileges.
Other means for allowing non-root users to
burn CDs do exist, but they are less secure, according to Jörg:
What some people did (chmod on /dev/ entries) was definitely always a bigger
security risk than running cdrecord suid root.
Another alternative, which is used by some distribution vendors (notably
Red Hat and SuSE), is to disallow non-root users from burning CDs; clearly this
is the most secure choice, but can be inconvenient for users and
system administrators. Many administrators and some CD burning front end programs override
this choice and, in this case,
that could lead to a large security hole that may not be patched by the
distribution. To avoid this possibility, some distributions have issued
cdrecord updates even though they do not install the program in a setuid
mode; see the LWN vulnerability
entry for the current list.
Jörg has fixed this bug in the most recent version of his cdrtools
package (2.01a38, available from his
cdrecord page).
The announcements for the new releases from the Mozilla project discussed
new features at length, but were silent on one other point: those releases
include fixes for a number of security vulnerabilities, some of which can
lead to remote code execution. See this
list of fixed vulnerabilities for several good reasons to upgrade.
Apache2 contains an integer error in the apr_uri_parse() function when handling IPv6 addresses. The result is a code execution vulnerability on BSD systems, and a denial of service vulnerability under Linux.
Versions of cups prior to 1.1.21 contain a denial of service vulnerability in their IPP implementation. A malicious UDP packet can cause cups to stop listening to the IPP port.
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.
There is a defect in smbd's ASN.1 parsing. A bad packet received during
the authentication request could throw newly-spawned smbd processes
into an infinite loop (CAN-2004-0807). Another defect was found in
nmbd's processing of mailslot packets, where a bad NetBIOS request
could crash the nmbd process (CAN-2004-0808). See this advisory for details.
SUS is a suid root program that allows ordinary users the execution of
certain programs with superuser privileges. SUS is run by default as setuid
root. A simple format string bug in the log() function allows any local
user to gain root privileges. See this
BugTraq advisory for more information.
There is an input validation bug in the webmail feature of Usermin.
Additionally, the Webmin and Usermin installation scripts write to
/tmp/.webmin without properly checking if it exists first.
The first vulnerability allows a remote attacker to inject arbitrary
shell code in a specially-crafted e-mail. This could lead to remote
code execution with the privileges of the user running Webmin or
Usermin.
The second could allow local users who know Webmin or Usermin is going
to be installed to have arbitrary files be overwritten by creating a
symlink by the name /tmp/.webmin that points to some target file, e.g.
/etc/passwd.
A stack-based buffer overflow exists in the ssl_util_uuencode_binary
function in ssl_util.c in Apache. When mod_ssl is configured to trust the
issuing CA, a remote attacker may be able to execute arbitrary code via a
client certificate with a long subject DN.
Aspell's word-list-compress utility fails to properly check bounds
when dealing with words that are more than 256 bytes long.
This can lead to arbitrary code execution by an attacker.
eGroupWare: cross site scripting vulnerabilities in modules
Package(s):
egroupware
CVE #(s):
Created:
September 2, 2004
Updated:
September 8, 2004
Description:
The eGroupWare has multiple vulnerabilities in the
calendar, address book, messenger and ticket modules.
An attacker can potentially execute script code and compromise
the victim's browser.
"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.
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.
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.
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.
Apache httpd has a denial of service vulnerability in mod_ssl in which
an attacker can force
an SSL connection to abort, resulting in the Apache child process entering
an infinite loop. This affects httpd versions up to and including
2.0.50.
Three separate vulnerabilities have been identified in the KDE 3.2
"kdebase" package; see this advisory for
details. These problems include two temporary file vulnerabilities and a
"frame injection" problem in konqueror which could help with phishing
attacks. In a fourth vulnerability, described here, Konqueror allows websites to set cookies
for certain country specific secondary top level domains.
During an audit of the Linux kernel, SUSE discovered a flaw that allowed
a user to make unauthorized changes to the group ID of files in certain
circumstances - such as when the files are exported via NFS.
Paul Starzetz discovered
flaws in the Linux kernel when handling file
offset pointers. These consist of invalid conversions of 64 to 32-bit file
offset pointers and possible race conditions. A local unprivileged user
could make use of these flaws to access large portions of kernel memory.
Note that this vulnerability affects all 2.4 kernels through 2.4.26 and 2.6 kernels through 2.6.7.
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 double-free bugs were found in the Kerberos 5 KDC and libraries. A
remote attacker could potentially exploit these flaws to execute arbitrary
code. See CAN-2004-0642, CAN-2004-0643 and CAN-2004-0772. An infinite
loop bug was found in the Kerberos 5 ASN.1 decoder library. A remote
attacker may be able to trigger this flaw and cause a denial of
service. See CAN-2004-0644. See this CERT
advisory for additional information.
The lha archiving and compression utility has a
stack-based buffer overflow vulnerability. A modified
archive could allow an attacker to execute code when a victim
extracts or test the archive.
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.
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.
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).
multi-gnome-terminal contains debugging code that has been known to
output active keystrokes to a potentially unsafe location. Output has
been seen to show up in the '.xsession-errors' file in the users home
directory. Since this file is world-readable on many machines, this bug
has the potential to leak sensitive information to anyone using the
system. Any authorized user on the local machine has the ability to read
any critical data that has been entered into the terminal, including
passwords.
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).
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."
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).
This August 2004 rsync
advisory reports that there is a path-sanitizing bug that affects
daemon mode in all recent rsync versions (including 2.6.2) but only if
chroot is disabled. It does NOT affect the normal send/receive filenames
that specify what files should be transferred (this is because these names
happen to get sanitized twice, and thus the second call removes any
lingering leading slash(es) that the first call left behind). It does
affect certain option paths that cause auxilliary files to be read or
written.
Andres Salomon noticed a problem in the CGI session management of Ruby, an
object-oriented scripting language. CGI::Session's FileStore (and
presumably PStore, but not in Debian woody) implementations store session
information insecurely. They simply create files, ignoring permission
issues. This can lead an attacker who has also shell access to the
webserver to take over a session.
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.
The NTLM authentication helper used by the squid proxy contains a buffer overflow vulnerability; an overly-long password may be used to run arbitrary code. Sites not using NTLM authentication are not vulnerable.
Several unspecified cross-site scripting (XSS) vulnerabilities and a well
hidden SQL injection vulnerability were found in SquirrelMail versions
1.4.2 and lower. An XSS attack allows an attacker to insert malicious code
into a web-based application. SquirrelMail does not check for code when
parsing variables received via the URL query string.
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.
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.
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.
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 September is out. Covered
topics include Beyond Fear, travel security, olympic security, and
the attacks against MD5 and SHA. "The techniques
described by the researchers are likely to have other applications, and
we'll be better able to design secure systems as a result. This is how
the science of cryptography advances: we learn how to design new
algorithms by breaking other algorithms. Additionally, algorithms from
the NSA are considered a sort of alien technology: they come from a
superior race with no explanations. Any successful cryptanalysis
against an NSA algorithm is an interesting data point in the eternal
question of how good they really are in there."
