The free software community operates under the assumption that security
problems are best addressed through full disclosure. Keeping
vulnerabilities secret is seen as a recipe for slower development and
deployment of fixes and the recurrence of the same mistakes in new
contexts. Many other groups, such as military organizations, take a
different approach: secrecy is a key part of how they maintain security.
The two approaches would appear to be contradictory; which is the right
one? Peter Swire has just published
a paper which attempts to answer this problem.
The paper sets the stage by trying to come up with ways of characterizing
the costs and benefits of disclosure. In any situation, how much does
disclosure of information benefit attackers and defenders? One of the core
observations made is that secrecy is most beneficial against first-time
attacks. When the defense has something unique or unknown (be it a
defensive technique or a vulnerability), secrecy can be effective. But
when it is possible to repeatedly probe defenses, and when defenses are not
unique, security through obscurity buys little. For this reason, computers
and networks tend to be more secure when operated in a full disclosure
mode.
Some exceptions are made, however. The paper goes to some lengths to make
the point that keys and passwords should be kept secret; it should not be
too hard to convince most readers of that. Mr. Swire also points out that
surveillance techniques can be a good candidate for secrecy; attackers can
often learn very little about monitoring systems by probing, so it is best
to keep them in the dark.
In the end, the paper takes few positions; the author will not commit
himself, for example, on whether free software is more or less secure than
proprietary software. As a framework for evaluating the value and costs of
disclosure, however, the paper may be a useful contribution.
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.
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.
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.
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.
iDEFENSE has reported that Adobe Acrobat Reader 5.0 contains a buffer
overflow when decoding uuencoded documents. An attacker could execute
arbitrary code on a victim's machine if a user opens a specially crafted
uuencoded document. This issue poses the threat of remote execution, since
Acrobat Reader may be the default handler for PDF files. The Common
Vulnerabilities and Exposures project has assigned the name CAN-2004-0631
to this issue.
iDEFENSE also reported that Adobe Acrobat Reader 5.0 contains an input
validation error in its uuencoding feature. An attacker could create a
file with a specially crafted file name which could lead to arbitrary
command execution on a victim's machine. The Common Vulnerabilities and
Exposures project has assigned the name CAN-2004-0630 to this issue.
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.
"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.
Gaim fails to do proper bounds checking in several instances. An attacker
could crash Gaim or execute arbitrary code or commands with the permissions
of the user running Gaim.
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.
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 2.6 kernel NFS and XDR code contains a number of integer overflow vulnerabilities which could be exploited (from a trusted address) for a denial of service attack.
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.
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.
MoinMoin contains a flaw that may allow a remote attacker to gain access to
unauthorized privileges. The issue is triggered due to a unspecified
function failing within the program, which could allow anonymous users to
gain administratively privileges, resulting in a loss of integrity. See
this OSVDB
advisory for more details. This has been fixed in MoinMoin version
1.2.3.
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 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.
According to this Samba advisory, Evgeny
Demidov discovered that the Samba SMB/CIFS server has a buffer overflow bug
in the Samba Web Administration Tool (SWAT) on decoding Base64 data during
HTTP Basic Authentication. Samba versions between 3.0.2 through 3.0.4 are
affected. (CAN-2004-0600)
Another buffer overflow bug has been located in the Samba code used to
support the "mangling method = hash" functionality. The default setting for
this parameter is "mangling method = hash2" and therefore Samba is not
vulnerable by default. Samba versions between 2.2.0 through 2.2.9 and 3.0.0
through 3.0.4 are affected. (CAN-2004-0686)
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.
