The OpenID project is an effort to
produce a decentralized, open, user-centric identity management framework.
The main benefit for users will be a 'single sign on' to websites that
support it. The project provides open source libraries for both
websites requiring authentication (relying parties) and for the
servers that provide the authentication (identity providers, IdPs).
One of the main goals is to allow anyone to run a server that authenticates
their own or others' identities and avoid the centralized model of other
identity frameworks.
At its core, OpenID allows a user to associate a URL with his or her identity;
a server can then authenticate that the user is the owner of that URL.
Giving users control of their own identity makes OpenID a user-centric
identity management system. To use OpenID authentication, the username
is the URL and the password is stored on the identity provider.
Thus, the same password is used to authenticate multiple accounts on
various websites.
There are different ways to use OpenID, depending on what the user's
requirements and capabilities are. In the simplest case, one can sign up
for a free account at a provider like
MyOpenID and it will generate a URL
for you to use (the author's test account was jake.edge.myopenid.com).
After that, you can submit that URL at any OpenID enabled website and
authenticate it. If you have not visited the site before, you
will be redirected to MyOpenID to enable that site to authenticate you.
You may also need to login to MyOpenID if you have not established a
session there recently. Once you have enabled authentication, you are redirected
back to the original site and MyOpenID will have authenticated you. If you have
a valid MyOpenID session and have previously enabled the site you are
visiting, you can be authenticated behind the scenes when you provide
your URL and will be able to log in without providing a password.
Another way to use a service like MyOpenID is by using a URL under your
control as your identity. By putting some HTML into the HEAD section of
the index document served from that URL, you can delegate the authentication
to another server and gain the benefits of
using your own URL without running your own OpenID server. If you do that,
the URL for OpenID logins becomes the URL under your control. Over time,
you could change the server that you delegate to while still retaining the
identity associated with your URL. In addition, various OpenID server
implementations exist for those who wish to fully control their identity
and can run their own server.
OpenID implements the authentication by using (but not requiring) strong
encryption on the messages that are exchanged between relying parties
and identity providers (IdPs). When a user enters a URL into
an OpenID login, the relying party makes a GET request to the URL and
expects to find some extra OpenID specific markup in the HEAD section. It
uses this markup to find the IdP and can negotiate an association between the
relying party and IdP, but does not have to. The association is an
agreement on cryptographic protocols to use to sign the requests and
responses. A relying party can then cache that information to use when
contacting that IdP for any other user that might share the server.
After that, the relying party redirects the user to the IdP which allows any
IdP specific cookies to be delivered. The IdP may decide to require the
user to authenticate with it, but that is outside of the scope of the OpenID
specification. As described above, the IdP may also require the user
to make a decision about whether to allow the relying party to authenticate
them. Once that is complete, the IdP returns the user to the relying party
site with an assertion about whether the authentication succeeded or failed.
The most recent OpenID
specification
adds some additional capabilities. A nonce (a unique identifier)
value was added as an option to the success response to thwart replay attacks.
Also, support for Yadis discovery was added.
Yadis allows relying parties to determine what authentication protocol
to use so that sites can transparently support other protocols such as
LID.
From a security standpoint, there are a few different attack vectors that
are described in the specification. Eavesdropping and man-in-the-middle
attacks can be circumvented by using HTTPS (SSL). Unless the IdP is
compromised, the identity itself is secure, though it could be spoofed
on a particular site using those vectors.
OpenID simply makes the connection between a URL and an identity,
it asserts that the two are associated, it does not provide any trust
information
about the identity. Users of OpenID will still have to prove they are
not programs at registration time because nothing in the protocol prevents
programs from having identities. It is a starting point, as any kind of
trust system must be based on an authenticated identity. A trust layer
that uses OpenID identities could provide protection against blog spam
and the like. Since OpenID identities can be anonymous, this will
allow for anonymous, but authenticated, users; one can verify that the
identity wrote a particular message without making a connection to the
real life person behind it.
There seems to be a growing number of
sites
that support OpenID; there is even a
bounty for adding support
to open source programs. Overall, it seems that OpenID provides a fairly
painless route for digital identity management for both users and websites.
It is probably worth a look for anyone that might be interested in such a
thing.
Will Drewry of the Google Security Team discovered several buffer overflows
in cscope, a source browsing tool, which might lead to the execution of
arbitrary code.
Input validation flaws have been discovered in the image handling of
fetch.php if ImageMagick is used, which is not the default method. A
remote attacker could exploit the flaws to execute arbitrary shell commands
with the rights of the web server daemon or cause a denial of service.
Jason Hoover discovered that migrationtools, a collection of scripts
to migrate user data to LDAP creates several temporary files insecurely,
which might lead to denial of service through a symlink attack.
The mono System.CodeDom.Compiler classes suffer from a temporary file symlink vulnerability which could be used to overwrite files, or, in this case, even inject arbitrary code into a running mono application.
slapd in OpenLDAP before 2.3.25 allows remote authenticated users with
selfwrite Access Control List (ACL) privileges to modify arbitrary
Distinguished Names (DN).
OpenSSL has a number of denial of service vulnerabilities including:
two vulnerabilities involving invalid ASN.1 structures, a buffer overflow
in the SSL_get_shared_ciphers() function and an SSLv2 client crash that
can be caused by a malicious server.
The Opera browser has a problem verifying OpenSSL PKCS #1
v1.5 RSA signatures. An attacker can use this to forge certificates
and appear as a valid CA.
From the Red Hat advisory: "A bug was found in Apache where an invalid Expect header sent to the server
was returned to the user in an unescaped error message. This could
allow an attacker to perform a cross-site scripting attack if a victim was
tricked into connecting to a site and sending a carefully crafted Expect
header."
The GNU assembler (gas) in binutils is vulnerable to a buffer overflow.
If a user can be tricked into assembling a specially crafted file with
gcc or gas, arbitrary code can be executed with the privileges of the user.
The BusyBox 1.1.1 passwd command does not use a proper salt when generating
passwords. This would create an instance where a brute force attack could
take very little time.
A race condition in bzip2 1.0.2 and earlier allows local users to modify
permissions of arbitrary files via a hard link attack on a file while it is
being decompressed, whose permissions are changed by bzip2 after the
decompression is complete. Also specially crafted bzip2 archives may cause
an infinite loop in the decompressor.
Lionel Elie Mamane discovered a security vulnerability in capi4hylafax,
tools for faxing over a CAPI 2.0 device, that allows remote attackers to
execute arbitrary commands on the fax receiving system.
Luigi Auriemma discovered a buffer overflow in the loading component
of cheesetracker, a sound module tracking program, which could allow a
maliciously constructed input file to execute arbitrary code.
Richard Harms discovered that cpio did not sufficiently validate file
properties when creating archives. Files with e. g. a very large size
caused a buffer overflow. By tricking a user or an automatic backup
system into putting a specially crafted file into a cpio archive, a
local attacker could probably exploit this to execute arbitrary code
with the privileges of the target user (which is likely root in an
automatic backup system).
The Vixie cron daemon does not check the return code from setuid(); if that call can be made to fail, a local attacker may be able to execute commands as root.
A buffer overflow in Cscope 15.5, and possibly multiple overflows, allows
remote attackers to execute arbitrary code via a C file with a long
#include line that is later browsed by the target.
Cyrus-SASL contains an unspecified vulnerability in the DIGEST-MD5
process that could lead to a Denial of Service. An attacker could possibly
exploit this vulnerability by sending specially crafted data stream to the
Cyrus-SASL server, resulting in a Denial of Service even if the attacker is
not able to authenticate.
the AVI processing code in FFmpeg has a number of buffer overflow
vulnerabilities.
If an attacker can trick a user into loading a specially crafted
crafted AVI, arbitrary code can be executed with the user's privileges.
Security issues were discovered in the Adobe Flash Player. It may be
possible to execute arbitrary code on a victim's machine if the victim
opens a malicious Adobe Flash file.
Several remote vulnerabilities have been discovered in freeradius, a
high-performance RADIUS server, which may lead to SQL injection or denial
of service.
The FreeType library has several integer overflow vulnerabilities.
If a user can be tricked into installing a specially
crafted font file, arbitrary code can be executed with the privilege
of the user.
The fastjar utility found in the GNU compiler collection does not perform adequate file path checking, allowing the creation or overwriting of files outside of the current directory tree.
A buffer overflow in dwarfread.c and dwarf2read.c debugging code in GNU
Debugger (GDB) 6.5 allows user-assisted attackers, or restricted users, to
execute arbitrary code via a crafted file with a location block
(DW_FORM_block) that contains a large number of operations.
A format string vulnerability has been discovered in gedit. Calling
the program with specially crafted file names caused a buffer
overflow, which could be exploited to execute arbitrary code with the
privileges of the gedit user.
Tavis Ormandy of the Google Security Team discovered two denial of service
flaws in the way gzip expanded archive files. If a victim expanded a
specially crafted archive, it could cause the gzip executable to hang or
crash.
Tavis Ormandy of the Google Security Team discovered several code execution
flaws in the way gzip expanded archive files. If a victim expanded a
specially crafted archive, it could cause the gzip executable to crash or
execute arbitrary code.
zgrep in gzip before 1.3.5 does not handle shell metacharacters like '|'
and '&' properly when they occurred in input file names. This could be
exploited to execute arbitrary commands with user privileges if zgrep is
run in an untrusted directory with specially crafted file names.
Kate / Kwrite, as shipped with KDE 3.2.x up to including 3.4.0, creates a file backup before saving a modified file. These backup files are created with default permissions, even if the original file had more strict permissions set. See this advisory for more information.
Sridhar Samudrala discovered a local denial of service vulnerability
in the handling of SCTP sockets. By opening such a socket with a
special SO_LINGER value, a local attacker could exploit this to crash
the kernel. (CVE-2006-4535)
Kirill Korotaev discovered that the ELF loader on the ia64 and sparc
platforms did not sufficiently verify the memory layout. By attempting
to execute a specially crafted executable, a local user could exploit
this to crash the kernel. (CVE-2006-4538)
The ftdi_sio driver (usb/serial/ftdi_sio.c) in Linux kernel 2.6.x up to
2.6.17, and possibly later versions, allows local users to cause a denial
of service (memory consumption) by writing more data to the serial port
than the driver can handle, which causes the data to be queued.
Previous versions of the kernel package are subject to several
vulnerabilities. Certain malformed UDF filesystems can cause the system to
crash (denial of service). Malformed CDROM firmware or USB storage devices
(such as USB keys) could cause system crash (denial of service), and if
they were intentionally malformed, can cause arbitrary code to run with
elevated privileges. In addition, the SCTP protocol is subject to a remote
system crash (denial of service) attack.
Some kerberos applications fail to check the results of setuid() calls, with the result that, if that call fails, they could continue to execute as root after thinking they had switched to a nonprivileged user. A local attacker who can cause these calls to fail (through resource exhaustion, presumably) could exploit this bug to gain root privileges.
Szymon Zygmunt and Michal Bartoszkiewicz discovered a memory alignment
error in libgadu (from ekg, console Gadu Gadu client, an instant
messaging program) which is included in gaim, a multi-protocol instant
messaging client, as well. This can not be exploited on the x86
architecture but on others, e.g. on Sparc and lead to a bus error,
in other words a denial of service.
Several buffer overflows were found in libmms. By tricking a user into
opening a specially crafted remote multimedia stream with an application
using libmms, a remote attacker could overwrite an arbitrary memory portion
with zeros, thereby crashing the program.
libpam-ldap, the PAM LDAP interface, has a vulnerability in which
it fails to authenticate with an LDAP server which is not configured
properly, allowing an authentication bypass.
In pngrutil.c, the function png_decompress_chunk() allocates
insufficient space for an error message, potentially overwriting stack
data, leading to a buffer overflow.
A heap based buffer overflow bug was found in the way libpng strips alpha
channels from a PNG image. An attacker could create a carefully crafted PNG
image file in such a way that it could cause an application linked with
libpng to crash or execute arbitrary code when the file is opened by a
victim.
The t2p_write_pdf_string function in libtiff 3.8.2 and earlier is vulnerable
to a buffer overflow. Attackers can use a TIFF file with UTF-8 characters
in the DocumentName tag to overflow a buffer, causing a denial of service,
and possibly the execution of arbitrary code.
LibVNCServer fails to properly validate protocol types effectively
letting users decide what protocol to use, such as "Type 1 - None".
LibVNCServer will accept this security type, even if it is not offered
by the server.
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.
An arbitrary command execute bug was found in the lynx "lynxcgi:" URI
handler. An attacker could create a web page redirecting to a malicious URL
which could execute arbitrary code as the user running lynx.
A flaw was found in the way Mailman handled MIME multipart messages. An
attacker could send a carefully crafted MIME multipart email message to a
mailing list run by Mailman which caused that particular mailing list
to stop working. (CVE-2006-2941)
Several cross-site scripting (XSS) issues were found in Mailman. An
attacker could exploit these issues to perform cross-site scripting attacks
against the Mailman administrator. (CVE-2006-3636)
Two flaws were found in the way Firefox/Thunderbird processed certain regular
expressions. A malicious web page/HTML email could crash the browser or
possibly execute arbitrary code as the user running
Firefox/Thunderbird. (CVE-2006-4565, CVE-2006-4566)
A number of flaws were found in Firefox/Thunderbird. A malicious web
page/HTML email could crash the browser or possibly execute arbitrary code
as the user running Firefox/Thunderbird. (CVE-2006-4571)
A flaw was found in the handling of JavaScript timed events. A malicious
web page could crash the browser or possibly execute arbitrary code as the
user running Firefox/Thunderbird. (CVE-2006-4253)
A flaw was found in the Firefox/Thunderbird auto-update verification
system. An attacker who has the ability to spoof a victim's DNS could get
Firefox to download and install malicious code. In order to exploit this
issue an attacker would also need to get a victim to previously accept an
unverifiable certificate. (CVE-2006-4567)
Firefox did not properly prevent a frame in one domain from injecting
content into a sub-frame that belongs to another domain, which facilitates
website spoofing and other attacks (CVE-2006-4568)
Firefox did not load manually opened, blocked popups in the right domain
context, which could lead to cross-site scripting attacks. In order to
exploit this issue an attacker would need to find a site which would frame
their malicious page and convince the user to manually open a blocked
popup. (CVE-2006-4569)
TAKAHASHI Tamotsu discovered that mutt's IMAP backend did not sufficiently
check the validity of namespace strings. If an user connects to a malicious
IMAP server, that server could exploit this to crash mutt or even execute
arbitrary code with the privileges of the mutt user. See this Secunia advisory for more
information.
Jean-David Maillefer discovered a format string bug in the
date_format() function's error reporting. By calling the function with
invalid arguments, an authenticated user could exploit this to crash
the server.
MySQL 4.1 before 4.1.21 and 5.0 before 5.0.24 allows a local user to access
a table through a previously created MERGE table, even after the user's
privileges are revoked for the original table, which might violate intended
security policy (CVE-2006-4031).
MySQL 4.1 before 4.1.21, 5.0 before 5.0.25, and 5.1 before 5.1.12, when run
on case-sensitive filesystems, allows remote authenticated users to create
or access a database when the database name differs only in case from a
database for which they have permissions (CVE-2006-4226).
MySQL 5.0.18 and earlier allows local users to bypass logging mechanisms
via SQL queries that contain the NULL character, which are not properly
handled by the mysql_real_query function. NOTE: this issue was originally
reported for the mysql_query function, but the vendor states that since
mysql_query expects a null character, this is not an issue for mysql_query.
Kurt Fitzner discovered that the NBD (network block device) server did not
correctly verify the maximum size of request packets. By sending specially
crafted large request packets, a remote attacker who is allowed to access
the server could exploit this to execute arbitrary code with root
privileges.
Daniel Bleichenbacher recently described an implementation error in RSA
signature verification. For RSA keys with exponent 3 it is possible for an
attacker to forge a signature that which would be incorrectly verified by
the NSS library.
Several vulnerabilities have been discovered in OpenOffice.org, a free
office suite.
It turned out to be possible to embed arbitrary BASIC macros in
documents in a way that OpenOffice.org does not see them but executes them
anyway without any user interaction. (CVE-2006-2198)
It is possible to evade the Java sandbox with specially crafted Java
applets. (CVE-2006-2199)
Loading malformed XML documents can cause buffer overflows and cause a
denial of service or execute arbitrary code. (CVE-2006-3117)
Openssh 4.4 fixes some
security issues, including a pre-authentication denial of service, an
unsafe signal hander and on portable OpenSSH a GSSAPI authentication abort
could be used to determine the validity of usernames on some platforms.
Philip Mackenzie, Marius Schilder, Jason Waddle and Ben Laurie of Google
Security discovered that the OpenSSL library did not sufficiently check the
padding of PKCS #1 v1.5 signatures if the exponent of the public key is 3
(which is widely used for CAs). This could be exploited to forge signatures
without the need of the secret key.
The file_exists and imap_reopen functions in PHP before 5.1.5 do not check
for the safe_mode and open_basedir settings, which allows local users to
bypass the settings (CVE-2006-4481).
A buffer overflow in the LWZReadByte function in ext/gd/libgd/gd_gif_in.c
in the GD extension in PHP before 5.1.5 allows remote attackers to have an
unknown impact via a GIF file with input_code_size greater than
MAX_LWZ_BITS, which triggers an overflow when initializing the table array
(CVE-2006-4484).
The stripos function in PHP before 5.1.5 has unknown impact and attack
vectors related to an out-of-bounds read (CVE-2006-4485).
It was discovered that phpbb2, a web based bulletin board, insufficiently
sanitizes values passed to the "Font Color 3" setting, which might lead to
the execution of injected code by admin users.
The phpbb2 web forum has a number of vulnerabilities including:
a web script injection problem, a protection mechanism bypass, a
security check bypass, a remote global variable bypass, cross site
scripting vulnerabilities, an SQL injection vulnerability,
a remote regular expression modification problem, missing input
sanitizing, and a missing request validation problem.
Stefan Esser reported multiple vulnerabilities
found in phpMyAdmin. The $GLOBALS variable allows modifying the global
variable import_blacklist to open phpMyAdmin to local and remote file
inclusion, depending on your PHP version (CVE-2005-4079, PMASA-2005-9).
Furthermore, it is also possible to conduct an XSS attack via the
$HTTP_HOST variable and a local and remote file inclusion because the
contents of the variable are under total control of the attacker
(CVE-2005-3665, PMASA-2005-8).
The PostgreSQL team has put out a set of "urgent updates" (in the form of the 7.3.15, 7.4.13, 8.0.8, and 8.1.4 releases) closing a
newly-discovered set of SQL injection issues. Details about the problem
can be found on the
technical information page; in short: multi-byte encodings can be used
to defeat normal string sanitizing techniques. The update fixes one problem
related to invalid multi-byte characters, but punts on another by simply
disallowing the old, unsafe technique of escaping single quotes with a
backslash.
Sendmail has a vulnerability in the way it handles multi-part MIME messages.
A remote attacker can create a specially crafted email message that can
be used to crash the sendmail process, causing a denial of service.
The useradd tool from the shadow-utils package has a potential security
problem. When a new user's mailbox is created, the permissions are
set to random garbage from the stack, potentially allowing the
file to be read or written during the time before fchmod() is called.
A vulnerability in jhot.php allows for an unrestricted file upload to
the img/wiki/ directory. Additionally, a cross-site scripting vulnerability
exists in the highlight parameter of tiki-searchindex.php.
A buffer overflow in UnZip 5.50 and earlier allows local users to execute
arbitrary code via a long filename command line argument. NOTE: since the
overflow occurs in a non-setuid program, there are not many scenarios under
which it poses a vulnerability, unless unzip is passed long arguments when
it is invoked from other programs.
xtensive testing of libwww's handling of multipart/byteranges content from
HTTP/1.1 servers revealed multiple logical flaws and bugs in
Library/src/HTBound.c
Webmin before 1.296 and Usermin before 1.226 does not properly handle a URL
with a null ("%00") character, which allows remote attackers to conduct
cross-site scripting (XSS), read CGI program source code, list directories,
and possibly execute programs.
Federico L. Bossi Bonin discovered a buffer overflow in the HTTP input
module. By tricking an user into opening a malicious remote media
location, a remote attacker could exploit this to crash Xine library
frontends (like totem-xine, gxine, or xine-ui) and possibly even
execute arbitrary code with the user's privileges.
xine-lib does an improper input data boundary check on
MPEG streams. A specially crafted MPEG file can be
created that can cause arbitrary code execution when the
file is accessed.
Several format string vulnerabilities have been discovered in xine-ui,
the user interface of the xine video player, which may cause a denial
of service.
Several X.org libraries and X.org itself contain system calls to
set*uid() functions, without checking their result. Local users could
deliberately exceed their assigned resource limits and elevate their
privileges after an unsuccessful set*uid() system call. This requires
resource limits to be enabled on the machine.
There is a buffer overflow in the Xrender extension of the X.Org server; any process which is able to connect to the server may be able to exploit this overflow to run arbitrary code. Since the X server runs as root on most systems, this vulnerability could be exploited to gain root access. See the X.Org advisory for more information.
iDefense reported two integer overflow
flaws in the way the X.org server processed CID font files. A malicious
authorized client could exploit this issue to cause a denial of service
(crash) or potentially execute arbitrary code with root privileges on the
X.org server.
xpdf has a number of integer overflows.
A remote attacker can trick a user into opening a maliciously
crafted pdf file, allowing the attacker to execute code with the
privileges of the local user.
This also affects the Poppler library, cupsys and tetex-bin.
