Let us start with a correction: last week's cvs
vulnerability timeline stated that no update had been issued for
CentOS. In fact, this
update was posted to the CentOS-devel mailing list on May 19. One
could argue that such updates should be posted to a more prominent place,
such as the CentOS web site or the
(seemingly dormant) security lists mentioned on the mailing lists page; one
should not have to follow a development list to get security updates. Nonetheless,
we were wrong to say that an update had not been released, and apologize
accordingly.
Now, however, the time has come to deal with a new set of cvs security
problems, as detailed in this advisory. A
whole list of issues has been found; many of those are remotely
exploitable. The time has come to apply a new set of updates, quickly.
(And, yes, CentOS has released
an update already).
Vulnerabilities in cvs are particularly scary. It is possible to run cvs
in a chroot mode, which is somewhat helpful in keeping an exploit from
leading to a full root compromise of the host system. But cvs servers must
have access to the code repositories they serve. It is not all that hard
to imagine a cvs exploit being the first step in the insertion of evil code
into a free software project's repository. A carefully executed malware
insertion could escape detection for a long time.
That sort of episode, beyond the immediate damage it would enable, would
not reflect well on the security of the free software development process
in general. We cannot afford to let it happen. With enough eyeballs, most
of the obvious security problems in cvs can probably be found and fixed.
That would help substantially.
The simple fact, however, is that cvs is not equipped to detect direct
tampering with its repositories. This shortcoming is sure to bite somebody
someday; the sooner it is fixed (or avoided by a mass shift to a more
contemporary version control system which performs integrity checks on its
repositories) the safer we all will be.
Several new vulnerabilities have been found in CVS; these include a null-termination error, a double-free vulnerability, a format-string vulnerability, and a few others; see this advisory for the details. Some of these vulnerabilities are remotely exploitable; updating soon would be a good idea.
Multiple buffer overflows exist in the krb5_aname_to_localname() library
function that if exploited could lead to unauthorized root privileges. In
order to exploit this flaw, an attacker must first successfully
authenticate to a vulnerable service, which must be configured to enable
the explicit mapping or rules-based mapping functionality of
krb5_aname_to_localname, which is not a default configuration. See the
this MIT krb5 Security Advisory for more information.
jaguar -at- felinemenace.org discovered a format string vulnerability in
log2mail, whereby a user able to log a specially crafted message to a
logfile monitored by log2mail (for example, via syslog) could cause
arbitrary code to be executed with the privileges of the log2mail process.
By default, this process runs as user 'log2mail', which is a member of
group 'adm' (which has access to read system logfiles).
A buffer overflow has been discovered in the ODBC driver of PostgreSQL,
an object-relational SQL database, descended from POSTGRES. It possible
to exploit this problem and crash the surrounding application. Hence, a
PHP script using php4-odbc can be utilized to crash the surrounding
Apache webserver. Other parts of postgresql are not affected.
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.
The code that generates email reports contains a format string
vulnerability in pipedmailmessage.cpp. With a carefully crafted filename
on a local filesystem an attacker could cause execution of arbitrary code
with permissions of the user running tripwire, which could be the root
user. See this advisory on SecurityFocus for more details.
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.
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).
"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.
The xatitv program, part of the gatos package, fails to drop root privileges after an initialization failure. For added fun, it then calls system() with unsanitized environment variables.
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.
jftpgw (an FTP proxy) contains a format string vulnerability which could allow the execution of arbitrary commands with the privileges of the server process.
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.
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.
MIT Kerberos 5 suffers from multiple buffer overflows which could lead to a remote root exploit, though the exploit looks difficult. Versions through krb5-1.3.3 are affected; see this advisory for more information.
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.
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 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).
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.
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."
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.
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.
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.
Jaguar discovered a vulnerability in one component of xpcd, a PhotoCD
viewer. xpcd-svga, part of xpcd which uses svgalib to display
graphics on the console, would copy user-supplied data of arbitrary
length into a fixed-size buffer in the pcd_open function.
The second New York City Security Shindig will be held the evening of
June 14. Jamie Butler will be speaking on kernel rootkits; additional
attractions include free pizza and non-free beer.
