OpenSSL is a well-advanced project
developing a free implementation of the Secure Socket Layer and Transport
Layer Security protocols. The OpenSSL code can be used in many contexts,
but the most prominent use is almost certainly in web servers which need to
offer the "https" protocol. When you (hint...) type your credit card
number at LWN.net, the OpenSSL code ensures that said number cannot be
captured by eavesdroppers lurking between your browser and our server.
OpenSSL is, in other words, a critical part of the net's infrastructure.
The central role played by OpenSSL makes any security vulnerabilities in
that package especially frightening. The software is widely deployed and
exposed directly to the net, so holes can open up large numbers of systems
to compromise. Sites using OpenSSL are also relatively likely to have
something worth protecting, and are thus also relatively likely to be
targets for certain types of crackers.
One would thus think that administrators of sites running OpenSSL would
tend to stay current
on their security updates. According to a
survey run by Netcraft, however, one would be wrong. Netcraft looked
at the advertised OpenSSL versions running on just over 50,000 web sites.
Fully half of those sites were running version 0.9.6d (or earlier), which
has vulnerabilities that are fully exploitable by a remote attacker. Only
1,356 out of 50,891 sites were running versions 0.9.6k or 0.9.7c, which
were, at the time, free of known vulnerabilities (a vulnerability
has since been found which can lead to crashes on Windows platforms).
OpenSSL users, it would seem, have not been keeping up with their patches.
As Netcraft acknowledges, the above results are overly pessimistic.
Security updates provided by distributors usually just backport the fix for
the specific problem(s) to the (older) version of the software that was
originally included in the distribution. So numerous sites which appear
(to the outside) to be running vulnerable software are, in fact, up to
date. Netcraft could have improved its numbers by seeing if an actual
exploit worked on each system tested, but that approach to data collection
has practical problems of its own.
The bottom line, however, is that there are certainly many vulnerable sites
out there. The fact that widespread exploits have not happened suggests
that the net is not quite as scary a place as it is sometimes made out to
be. But, sooner or later, an opening of this magnitude will certainly be
exploited. Whether it is used for some sort of unpleasant worm or for a
credit card scam doesn't really matter. Either way, it will impair the
trust in Linux, Apache, and network commerce in general. And it is
entirely avoidable.
If you have systems running older versions of OpenSSL, it is past time to
update them. The LWN
vulnerability entry will point you at the relevant distributor
updates.
Several new vulnerabilities have been found in bugzilla; these include a pair of SQL injection bugs (usually only exploitable by privileged users) and some information leaks. See this advisory for details; upgrading to versions 2.16.4 or 2.17.5 fixes the problems.
Paul Mitcheson reported a situation where the CUPS Internet Printing
Protocol (IPP) implementation in CUPS versions prior to 1.1.19 would get
into a busy loop. This could result in a denial of service. In order to
exploit this bug an attacker would need to have the ability to make a TCP
connection to the IPP port (by default 631).
Two bugs leading to a buffer overflow in the PostgreSQL RDBMS, versions 7.2.x and
7.3.x prior to 7.3.4, were discovered. The vulnerability exists in the
PostgreSQL abstract data type (ADT) to ASCII conversion functions.
It has been conjectured that excessive data passed to the involved
to_ascii_xxx() functions may overrun the bounds of an insufficient buffer
reserved in heap memory, resulting in the corruption of heap based memory
management structures that are adjacent to it. It is currently believed
that under the correct circumstances an attacker may use this to execute
arbitrary instructions in the context of the PostgreSQL server.
The Common Vulnerabilities and Exposures (CVE) project assigned the id
CAN-2003-0901 to the problem.
Several security issues have been discovered affecting the Linux kernel:
CAN-2003-0461: /proc/tty/driver/serial reveals the exact character
counts for serial links. This could be used by a local attacker to infer
password lengths and inter-keystroke timings during password entry.
CAN-2003-0462: Paul Starzetz discovered a file read race condition
existing in the execve() system call, which could cause a local crash.
CAN-2003-0464: A recent change in the RPC code set the reuse flag on
newly-created sockets. Olaf Kirch noticed that his could allow normal
users to bind to UDP ports used for services such as nfsd.
CAN-2003-0476: The execve system call in Linux 2.4.x records the file
descriptor of the executable process in the file table of the calling
process, allowing local users to gain read access to restricted file
descriptors.
CAN-2003-0501: The /proc filesystem in Linux allows local users to
obtain sensitive information by opening various entries in /proc/self
before executing a setuid program. This causes the program to fail to
change the ownership and permissions of already opened entries.
CAN-2003-0550: The STP protocol is known to have no security, which
could allow attackers to alter the bridge topology. STP is now turned
off by default.
CAN-2003-0551: STP input processing was lax in its length checking,
which could lead to a denial of service.
CAN-2003-0552: Jerry Kreuscher discovered that the Forwarding table
could be spoofed by sending forged packets with bogus source addresses
the same as the local host.
Another buffer overflow in Apache 2.0.47 and earlier in mod_cgid's
mishandling of CGI redirect paths could result in CGI output going to the
wrong client when a threaded MPM is used.
CAN-2003-0789.
A problem was discovered in Apache2 where CGI scripts that write more than
4k to the standard error stream will hang the script's execution. This problem can lead to a
denial of service situation. See this bug
report for additional details.
Several security problems have been found in Ethereal
0.9.12. "It may be possible to make Ethereal crash or run
arbitrary code by injecting a purposefully malformed packet onto the wire,
or by convincing someone to read a malformed packet trace file."
"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, it seems, an integer overflow vulnerability in "ls" which can be exploited via wu-ftpd to create a denial of service situation. See this advisory from Georgi Guninski for details.
The GNU C library contains a buffer overflow in the getgrouplist() function. If the user belongs to more groups than the calling application expects, the allocated storage will be overrun.
DNS stub resolvers from multiple vendors contain a buffer overflow
vulnerability. The impact of this vulnerability appears to be limited to
denial of service. (See CERT Vulnerability Note
VU#738331)
The BIND 4 and BIND 8.2.x stub resolver libraries, and other libraries such
as glibc 2.2.5 and earlier, libc, and libresolv, uses the maximum buffer
size instead of the actual size when processing a DNS response, which
causes the stub resolvers to read past the actual boundary ("read buffer
overflow"), allowing remote attackers to cause a denial of service
(crash).
A key validation bug was discovered in the GNU Privacy Guard (GPG) which
would cause keys with more then one user ID to trust all user ID's with the
amount of trust given to the most-valid user ID.
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.
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:
libnids (a NIDS plugin which emulates the Linux 2.0 IP stack) contains a buffer overflow vulnerability which can be exploited remotely. Version 1.18 fixes the problem.
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.
A remotely exploitable buffer overflow vulnerability was found in
MPlayer. A malicious host can craft a harmful ASX header, and trick MPlayer
into executing arbitrary code upon parsing that header. Read the full advisory
for details.
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.
Linux NFS utils package contains remotely exploitable off-by-one bug.
A local or remote attacker could exploit this vulnerability by sending
specially crafted request to rpc.mountd daemon. See this BugTraq post for more details.
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."
Vulnerabilities have been found in OpenSSL ASN.1 code. This advisory contains details of 4 separate
problems in versions of OpenSSL up to and including 0.9.6j and 0.9.7b and
all versions of SSLeay.
An attack against other applications that use OpenSSL could result in a
Denial of Service. See
CAN-2003-0543 and
CAN-2003-0544.
It may be possible for an attacker to exploit this issue to execute
arbitrary code. See
CAN-2003-0545.
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 new set of buffer overflows has been discovered in PostgreSQL 7.2.2; they affect the circle_poly(), path_encode(), and path_addr() functions. Exploiting these overflows requires that the attacker first obtain a connection to the PostgreSQL server.
The ASCII translation mechanism in ProFTPD 1.2.8 contains a vulnerability which will provide a remote attacker with a root shell - if the attacker is able to download a specially-crafted file. See this ISS advisory for more information.
usePerl has a
description of a vulnerability in the Safe.pm Perl module. It seems
that if a Safe compartment is used more than once, it ceases to be safe.
The problem is fixed in Safe 2.08.
Alexander Hvostov, Julien Blache and Aurelien Jarno discovered several
security-related problems in the sane-backends package, which contains
an API library for scanners including a scanning daemon (in the
package libsane) that can be remotely exploited. These problems allow
a remote attacker to cause a segfault fault and/or consume arbitrary
amounts of memory. The attack is successful, even if the attacker's
computer isn't listed in saned.conf.
You are only vulnerable if you actually run saned e.g. in xinetd or
inetd. If the entries in the configuration file of xinetd or inetd
respectively are commented out or do not exist, you are safe.
Try "telnet localhost 6566" on the server that may run saned. If you
get "connection refused" saned is not running and you are safe.
The Common Vulnerabilities and Exposures project identifies the
following problems:
CAN-2003-0773: saned checks the identity (IP address) of the remote
host only after the first communication took place (SANE_NET_INIT). So
everyone can send that RPC, even if the remote host is not allowed to
scan (not listed in saned.conf).
CAN-2003-0774: saned lacks error checking nearly everywhere in the
code. So connection drops are detected very late. If the drop of the
connection isn't detected, the access to the internal wire buffer leaves
the limits of the allocated memory. So random memory "after" the wire
buffer is read which will be followed by a segmentation fault.
CAN-2003-0775: If saned expects strings, it mallocs the memory
necessary to store the complete string after it receives the size of the
string. If the connection was dropped before transmitting the size,
malloc will reserve an arbitrary size of memory. Depending on that size
and the amount of memory available either malloc fails (->saned quits
nicely) or a huge amount of memory is allocated. Swapping and OOM
measures may occur depending on the kernel.
CAN-2003-0776: saned doesn't check the validity of the RPC numbers
it gets before getting the parameters.
CAN-2003-0777: If debug messages are enabled and a connection is
dropped, non-null-terminated strings may be printed and segmentation
faults may occur.
CAN-2003-0778: It's possible to allocate an arbitrary amount of
memory on the server running saned even if the connection isn't dropped.
At the moment this can not easily be fixed according to the author.
Better limit the total amount of memory saned may use (ulimit).
Michal Zalewski has reported a buffer overflow in sendmail. This overflow, apparently, may be exploited remotely, but only in certain (non-default) configurations. Sendmail 8.12.10 has the fix.
Stunnel is a wrapper for network connections. It can be used to tunnel an
unencrypted network connection over a secure connection (encrypted using
SSL or TLS) or to provide a secure means of connecting to services that do
not natively support encryption.
When configured to listen for incoming connections (instead of being
invoked by xinetd), stunnel can be configured to either start a thread or a
child process to handle each new connection. If Stunnel is configured to
start a new child process to handle each connection, it will receive a
SIGCHLD signal when that child exits.
Stunnel versions prior to 4.04 would perform tasks in the SIGCHLD signal
handler which, if interrupted by another SIGCHLD signal, could be unsafe.
This could lead to a denial of service.
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.
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.
The thttpd web server has a pair of vulnerabilities which can lead to information disclosure and arbitrary code execution; both are remotely exploitable.
A vulnerabilitiy in unzip version 5.50 and earlier allows attackers to
overwrite arbitrary files during archive extraction by placing invalid
(non-printable) characters between two "." characters. These non-printable
characters are filtered, resulting in a ".." sequence. See the full
advisory for further information.
VIM allows a user to set the modeline differently for each edited text file
by placing special comments in the files. Georgi Guninski found that these
comments can be carefully crafted in order to call external programs. This
could allow an attacker to create a text file such that when it is opened
arbitrary commands are executed.
miniserv.pl in the webmin package does not properly handle
metacharacters, such as line feeds and carriage returns, in
Base64-encoded strings used in Basic authentication. This
vulnerability allows remote attackers to spoof a session ID, and
thereby gain root privileges.
Several vulnerabilities were discovered by blexim(at)hush.com in the font
libraries of XFree86 version 4.3.0 and earlier. These bugs could
potentially lead to execution of arbitrary code or a DoS by a remote user
in any way that calls these functions, which are related to the transfer
and enumeration of fonts from font servers to clients. See the
advisory for additional details.
Xinetd is a 'master server' that is used to to accept service connection
requests and start the appropriate servers.
Because of a programming error, memory was allocated and never freed if a
connection was refused for any reason. An attacker could exploit this flaw
to crash the xinetd server, rendering all services it controls unavailable.
In addition, other flaws in xinetd could cause incorrect operation in
certain unusual server configurations.
All users of xinetd are advised to update to xinetd-2.3.11 which is not
vulnerable to these issues.
