Anonymity and deniability in distributing information are two of the goals
of the GNUnet project. Recently revamped to
use a new content encoding called
Encoding for Censorship-Resistant
Sharing (ECRS), GNUnet has released version 0.7.0 with an eye towards a
stable version sometime during the next year.
At its heart, GNUnet is a mechanism to share content with others without
revealing who generated the content or who accessed it. It also
provides intermediate nodes in the network with the ability to deny
knowledge of the contents of any traffic they forward because they are
unable to decrypt it.
Anonymity relies on there being a large number of nodes participating in
the network, forwarding traffic for each other. The GNUnet protocol
attempts to make all traffic look the same, whether it is satisfying
a request for information that resides locally or forwarding a request
or response from another peer
in the network. When traffic is light, GNUnet will delay requests to
accumulate enough traffic before sending to other peers making it difficult
for external analysis to pin down which peers are communicating and what
content is being transferred.
Only the requester of content has the key necessary to decrypt the content
which provides deniability for intermediate peers.
In the default configuration, GNUnet peers
automatically migrate content from the node where they were inserted to
other peers. In the event that some hostile entity gets
control of the node, breaks the encryption and determines the content
stored by the node, node operators can plausibly claim
that they had no knowledge of or control over the content stored on
their node.
Once content has been inserted into GNUnet, users can search by keywords
to find content of interest. ECRS guarantees that intermediaries cannot
see the keyword being searched without guessing the keyword, applying the
query hash and comparing the result. Only peers that have content with
that keyword (or have guessed it) can generate valid responses. GNUnet
depends on content providers generating proper keywords for their
content and nothing in the protocols stops malicious peers from generating
valid query results for a multitude of keywords. Easy to guess keywords
could easily be overwhelmed by bogus results.
Namespaces provide resistance to the keyword spamming attack by generating
keyword spaces that are cryptographically signed by some entity. That
entity generates a public-private key pair (known as a pseudonym) and signs
the content. Other users can form opinions about the trustworthiness of
content in that namespace and can use that information to further restrict
their search.
GNUnet tries to eliminate freeloading peers by relying on a trust-based
economic model. If a node gets busy and has more requests than it can
satisfy based on the amount of CPU and bandwidth its operator has allocated
to GNUnet, it will drop requests from peers that it trusts least. Peers gain
trust by satisfying query requests and lose trust by requesting content.
Because ECRS can determine that a query response is valid without being
able to decrypt the content, it resists attempts to gain trust by
providing bogus results.
Much like other systems designed to promote anonymous speech, some of which
were described in an LWN
article two years ago, GNUnet
suffers from a very slow user experience. Keyword searches can take many
minutes to return results and downloading the content often takes a huge
amount of time. In addition, the content available with some simple
searches left a great deal to be desired. There appears to be very little
of consequence available.
On the other hand, GNUnet does seem to have some excellent approaches to
handling censorship and spamming kinds of attacks that have hampered other
approaches to this problem. It seems to provide a very reasonable framework
for anonymous content sharing that would be of use to groups that wish to
circumvent the policies of authoritarian regimes. Unfortunately, deniability
is only likely to work in places that have relatively sane legal systems and
there are probably many places in the world where just having GNUnet running
on one's machine is enough to be branded as a criminal.
Wernfried Haas discovered that centericq, a text-mode multi-protocol
instant messenger client, can crash when it receives certain zero
length packets and is directly connected to the Internet.
Horde has a potential cross site scripting vulnerability.
Error messages are not properly escaped. A user can be tricked
into executing arbitrary scripts by reading specially crafted
email messages, or using a maliciously created URL.
The MIME viewer in the horde3 web
application suite has an input sanitizing vulnerability.
It is possible for a remote attacker to use this to execute
arbitrary code.
The cursel iptables/iproute2 GUI ipmenu has a vulnerability
involving the creation of an insecure temporary file.
A local attacker can overwrite arbitrary files by performing
a symlink attack.
A vulnerability has been discovered in zope 2.7 that allows remote
attackers to insert arbitrary files via include directives in
reStructuredText functionality.
The GNU a2ps utility fails to properly sanitize filenames, which can be
abused by a malicious user to execute arbitrary commands with the
privileges of the user running the vulnerable application. More
information at Security
Focus.
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.
There is a vulnerability in
cpio (2.6 and previous) that allows a malicious cpio file to
extract to an arbitrary directory of the attackers choice. cpio will
extract to the path specified in the cpio file, this path can be absolute.
Cyrus-imapd, prior to version 2.2.12, contains several buffer overflows which could be exploited by an (authenticated) attacker to run code on the server system.
Joxean Koret discovered that the SVG import plugin did not properly
sanitize data read from an SVG file. By tricking an user into opening
a specially crafted SVG file, an attacker could exploit this to
execute arbitrary code with the privileges of the user.
A number of vulnerabilities have been found in egroupware,
a web-based groupware suite.
Phpsysinfo has several cross-site scripting vulnerabilities,
The the tree view of FUD Forum Bulletin Board Software has
a cross-site scripting problem, phpsyinfo has a local variable
overwrite problem, and phpsyinfo has an input sanitizing
issue.
Max Vozeler discovered a format string vulnerability in the "movemail"
utility of Emacs. By sending specially crafted packets, a malicious
POP3 server could cause a buffer overflow, which could be exploited to
execute arbitrary code with the privileges of the user and the "mail"
group.
The key selection dialog from the Mozilla Thunderbird enigmail plugin
has an information disclosure vulnerability.
A key with an empty user id from a user's keyring will be used by
default, allowing a message to be decrypted. This can lead to an
unauthorized information disclosure.
Erik Sjölund has discovered several security relevant problems in enscript,
a program to convert ASCII text into Postscript and other formats.
Unsanitized input can cause the execution of arbitrary commands via EPSF
pipe support. Due to missing sanitizing of filenames it is possible that a
specially crafted filename can cause arbitrary commands to be executed.
Multiple buffer overflows can cause the program to crash.
A number of security flaws have been discovered in Ethereal. On a system
where Ethereal is running, a remote attacker could send malicious packets
to trigger these flaws and cause Ethereal to crash or potentially execute
arbitrary code.
The Firefox browser has multiple vulnerabilities including problems with
XBM image file processing, Unicode
sequence processing, XMLHttp requests, malicious XBL binding,
a JavaScript engine buffer overflow, about: pages,
opening of new windows, and command line URL processing.
The Mozilla browser Macromedia Flash Player plug-in has a
buffer overflow vulnerability. A user who opens a maliciously
created Macromedia Flash file may be tricked into executing
arbitrary code.
There is a vulnerability in the foomatic-filters package. This
vulnerability is due to insufficient checking of command-line parameters
and environment variables in the foomatic-rip filter. This vulnerability
may allow both local and remote attackers to execute arbitrary commands on
the print server with the permissions of the spooler.
Thomas Biege discovered that fusermount fails to securely handle
special characters specified in mount points. A local attacker could corrupt the contents of the /etc/mtab file by mounting over a maliciously-named directory using fusermount, potentially allowing the attacker to set unauthorized mount options.
Tavis Ormandy of the Gentoo Linux Security Audit Team discovered an integer
overflow in the BFD library, resulting in a heap overflow. A review also
showed that by default, gdb insecurely sources initialization files from
the working directory. Successful exploitation would result in the
execution of arbitrary code on loading a specially crafted object file or
the execution of arbitrary commands.
The gdk-pixbuf package contains an image loading library used with the
GNOME GUI desktop environment. A bug was found in the way gdk-pixbuf
processes XPM images. An attacker could create a carefully crafted XPM file
in such a way that it could cause an application linked with gdk-pixbuf to
execute arbitrary code when the file was opened by a victim.
Ludwig Nussel discovered an integer overflow bug in the way gdk-pixbuf
processes XPM images. An attacker could create a carefully crafted XPM
file in such a way that it could cause an application linked with
gdk-pixbuf to execute arbitrary code or crash when the file was opened by a
victim.
Ludwig Nussel also discovered an infinite-loop denial of service bug in the
way gdk-pixbuf processes XPM images. An attacker could create a carefully
crafted XPM file in such a way that it could cause an application linked
with gdk-pixbuf to stop responding when the file was opened by a victim.
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.
gettext insecurely creates temporary files in world-writeable directories
with predictable names. A local attacker could create symbolic links in
the temporary files directory, pointing to a valid file somewhere on the
filesystem. When gettext is called, this would result in file access with
the rights of the user running the utility, which could be the root user.
Recently, Trustix Secure Linux discovered a vulnerability in the groff
package. The utility "groffer" created a temporary directory in an
insecure way, which allowed exploitation of a race condition to create
or overwrite files with the privileges of the user invoking the
program.
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.
Michael Krax discovered that ht://Dig fails to validate the 'config'
parameter before displaying an error message containing the parameter.
This flaw could allow an attacker to conduct cross-site scripting
attacks.
A buffer overflow flaw was found in the c-client IMAP client. An attacker
could create a malicious IMAP server that if connected to by a victim could
execute arbitrary code on the client machine.
A buffer overflow has been discovered in the SVG importer of Inkscape.
By tricking an user into opening a specially crafted SVG image this
could be exploited to execute arbitrary code with the privileges of
the Inkscape user.
The kdebase package (and kcheckpass in particular) found in KDE versions 3.2.0 through 3.4.2 suffers from a lock file handling error which can enable a local attacker to obtain root access. See this advisory for details.
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.
A number of vulnerabilities have been found in the Linux kernel, including a PPP-related denial of service problem, an integer overflow in the epoll() code, memory corruption in the ELF loader, and exploitable overflows in the ISO9660 code.
Al Viro discovered a race condition in the /proc file handler of
network devices. A local attacker could exploit this by opening any
file in /proc/sys/net/ipv4/conf/<interface>/ and waiting until that
interface was shut down. Under certain circumstances this could lead
to a kernel crash or even arbitrary code execution with full kernel
privileges. (CVE-2005-2709)
Tetsuo Handa discovered a local Denial of Service vulnerability in the
udp_v6_get_port() function. On computers which use IPv6, a local
attacker could exploit this to trigger an infinite loop in the kernel.
(CVE-2005-2973)
Harald Welte discovered a Denial of Service vulnerability in the USB
devio driver. A local attacker could exploit this by sending an "USB
Request Block" (URB) and terminating the sending process before the
arrival of the answer, which left an invalid pointer and caused a
kernel crash. (CVE-2005-3055)
Pavel Roskin discovered an information leak in the Orinoco wireless
card driver. When increasing the buffer length for storing data, the
buffer was not padded with zeros, which exposed a random part of the
system memory to the user. (CVE-2005-3180)
A resource leak has been discovered in the handling of POSIX timers in
the exec() function. This could be exploited to a Denial of Service
attack by a group of local users. (CVE-2005-3271)
Stephen Hemminger discovered a weakness in the network bridge driver.
Packets which had already been dropped by the packet filter could
poison the forwarding table, which could be exploited to make the
bridge forward spoofed packages. (CVE-2005-3272)
David S. Miller discovered a buffer overflow in the rose_rt_ioctl()
function. By calling the function with a large "ngidis" argument, a
local attacker could cause a kernel crash. (CVE-2005-3273)
Neil Horman discovered a race condition in the connection timer
handling. This allowed a local attacker to set up an expiration
handler which modified the connection list while the list still being
traversed, which could result in a kernel crash. This vulnerability
only affects multiprocessor (SMP) systems. (CVE-2005-3274)
Patrick McHardy noticed a logic error in the network address
translation (NAT) connection tracker. A remote attacker could exploit
this by causing two packets for the same protocol to be NATed at the
same time, which resulted in a kernel crash. (CVE-2005-3275)
Paolo Giarrusso discovered an information leak in the
sys_get_thread_area(). The returned structure was not properly
cleared, which exposed a small amount of kernel memory to userspace
programs. This could possibly expose confidential data.
(CVE-2005-3276)
The krb5 authentication has a double-free flaw which may be
initiated by a remote unauthenticated attacker.
Also, a single byte heap overflow in the krb5_unparse_name() function
can lead to a denial of service and an information disclosure may
be caused by a malicious telnet server. See
This report for more
information.
Mark Martinec and Robert Lewis discovered a buffer overflow in
Convert::UUlib (before 1.051), a Perl interface to the uulib library, which
may result in the execution of arbitrary code.
Javier Fernández-Sanguino Peña from the Debian Security Audit Project
discovered that the DBI library, the Perl5 database interface, creates
a temporary PID file in an insecure manner. This can be exploited by a
malicious user to overwrite arbitrary files owned by the person
executing the parts of the library.
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 have been discovered in libgd's PNG handling
functions.
If an attacker tricked a user into loading a malicious PNG image, they
could leverage this into executing arbitrary code in the context of
the user opening image. Most importantly, this library is commonly
used in PHP. One possible target would be a PHP driven photo website
that lets users upload images. Therefore this vulnerability might lead
to privilege escalation to a web server's privileges.
Multiple buffer overflows in the gd graphics library (libgd) 2.0.21 and
earlier may allow remote attackers to execute arbitrary code via malformed
image files that trigger the overflows due to improper calls to the
gdMalloc function.
Javier Fernandez-Sanguino Pena discovered that this library used the
file /tmp/entropy as a fallback entropy source if a proper source was
not set in the environment variable EGD_PATH. This can potentially
lead to weakened cryptographic operations if an attacker provides a
/tmp/entropy file with known content.
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.
Tavis Ormandy of the Gentoo Linux Security Audit Team discovered a
stack based buffer overflow in the libTIFF library when reading a TIFF
image with a malformed BitsPerSample tag. Successful exploitation would
require the victim to open a specially crafted TIFF image, resulting in the
execution of arbitrary code.
The libungif library has a vulnerability in the GIF file
colormap handling code. A maliciously crafted GIF file can
cause out of bounds memory writing and register corruption.
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.
Mantis contains several vulnerabilities, including a remote file inclusion
vulnerability, an SQL injection vulnerability, multiple cross site
scripting vulnerabilities and multiple information disclosure
vulnerabilities.
mod_python has a vulnerability in the publisher handler that may allow
a remote user to use a specially crafted URL to allow access to
objects that should be protected. An information leak can result.
The mysql CREATE FUNCTION can be used to create a buffer overflow.
A specially crafted long function name can be used by a local attacker
to crash the server or execute arbitrary code with the privileges of
the server.
Erik Sjolund discovered two vulnerabilities in the programs bundled
with ncpfs: there is a potentially exploitable buffer overflow in
ncplogin (CAN-2005-0014), and due to a flaw in nwclient.c, utilities
using the NetWare client functions insecurely access files with
elevated privileges (CAN-2005-0013).
Greg Roelofs discovered and fixed several buffer overflows in pnmtopng
which is also included in netpbm, a collection of graphic conversion
utilities, that can lead to the execution of arbitrary code via a
specially crafted PNM file.
Arjan van de Ven discovered a buffer overflow in rquotad on 64bit
architectures; an improper integer conversion could lead to a buffer
overflow. An attacker with access to an NFS share could send a specially
crafted request which could then lead to the execution of arbitrary code.
When starting xntpd with the -u option and specifying the
group by using a string not a numeric gid the daemon uses
the gid of the user not the group. This problem is now fixed
by this update.
OpenSSH prior to version 4.2 will allow GSSAPI credentials to be delegated to users who are not using GSSAPI authentication, possibly leading to the unwanted disclosure of those credentials. OpenSSH 4.2 has the fix.
OpenSSL prior to version 0.9.7h or 0.9.8a contains a vulnerability which could enable an attacker to force the use of the older, less secure SSL 2.0 protocol. See this advisory for details or this analysis for even more details.
A buffer overflow has been discovered in the PCRE, a widely used library
that provides Perl compatible regular expressions. Specially crafted
regular expressions triggered a buffer overflow. On systems that accept
arbitrary regular expressions from untrusted users, this could be exploited
to execute arbitrary code with the privileges of the application using the
library.
There are two vulnerabilities with perl when it is used in a setuid mode. The PERLIO_DEBUG environment variable can be used to overwrite arbitrary files; there is also an associated buffer overflow which can be exploited to gain root access.
There are multiple vulnerabilities in PHP, including malicious requests may overwrite the GLOBALS array, the parse_str() function may enable the
register_globals setting, cross-site scripting bugs in phpinfo() and a bug in EXIF image parsing that may crash the process.
Christopher Kunz discovered that local variables get overwritten
unconditionally and are trusted later, which could lead to the inclusion of
arbitrary files. Christopher Kunz also discovered that user-supplied input
is used unsanitized, causing a HTTP Response splitting problem.
PostgreSQL suffers from two vulnerabilities in how databases are set up by default; they allow a local attacker (one with access to the database) to crash the back end and, perhaps, execute code with the privileges of the server process. See this advisory for details and workarounds.
Steven Van Acker has discovered a buffer overflow vulnerability in the
"add_port()" function in Pound 1.8.2+. A remote attacker could send a
request for an overly long hostname parameter, which could lead to the
remote execution of arbitrary code with the rights of the Pound daemon
process.
Max Vozeler reported that pstotext calls the GhostScript interpreter on
untrusted PostScript files without specifying the -dSAFER option. An
attacker could craft a malicious PostScript file and entice a user to run
pstotext on it, resulting in the execution of arbitrary commands with the
permissions of the user running pstotext. See this Secunia advisory for more information.
Py2Play uses Python pickles to send objects over a peer-to-peer game network, that clients accept without restriction the objects and code sent by peers. A remote attacker participating in a Py2Play-powered game can send
malicious Python pickles, resulting in the execution of arbitrary
Python code on the targeted game client.
Luigi Auriemma discovered multiple flaws in the Scorched 3D game
server, including a format string vulnerability and several buffer
overflows. A remote attacker could exploit these vulnerabilities to crash
a game server or execute arbitrary code with the rights of the game server
user.
Upstream developers of squid, the popular WWW proxy cache, have
discovered that changes in the authentication scheme are not handled
properly when given certain request sequences while NTLM
authentication is in place, which may cause the daemon to restart.
Tavis Ormandy noticed that sudo, a program that provides limited super
user privileges to specific users, does not clean the environment
sufficiently. The SHELLOPTS and PS4 variables are dangerous and are
still passed through to the program running as privileged user. This
can result in the execution of arbitrary commands as privileged user
when a bash script is executed. These vulnerabilities can only be
exploited by users who have been granted limited super user
privileges.
Charles Morris discovered a race condition in sudo which could lead to
privilege escalation. If /etc/sudoers allowed a user the execution of
selected programs, and this was followed by another line containing
the pseudo-command "ALL", that user could execute arbitrary commands
with sudo by creating symbolic links at a certain time.
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.
The rsvp_print function in tcpdump 3.9.1 and earlier allows remote
attackers to cause a denial of service (infinite loop) via a crafted RSVP
packet of length 4. (CAN-2005-1280)
tcpdump 3.8.3 and earlier allows remote attackers to cause a denial of
service (infinite loop) via a crafted BGP packet, which is not properly
handled by RT_ROUTING_INFO, or LDP packet, which is not properly
handled by the ldp_print function. (CAN-2005-1279)
The isis_print function, as called by isoclns_print, in tcpdump 3.9.1 and
earlier allows remote attackers to cause a denial of service (infinite
loop) via a zero length, as demonstrated using a GRE packet.
(CAN-2005-1278)
A denial of service bug was found in the way ucd-snmp uses network stream
protocols. A remote attacker could send a ucd-snmp agent a specially
crafted packet which will cause the agent to crash.
Masanari Yamamoto discovered that Uim uses environment variables
incorrectly. This bug causes a privilege escalation if setuid/setgid
applications are linked to libuim. This bug only affects
immodule-enabled Qt (if you build Qt 3.3.2 or later versions with
USE="immqt" or USE="immqt-bc").
Unzip has a race condition vulnerability
in the handling of output files.
During file unpacking, a local attacker can modify the permissions
of arbitrary files in the victim's directory.
Linux umount command as provided in the util-linux package in
versions 2.8 to 2.12q, 2.13-pre1 and 2.13-pre2 grants root privileges. See this BugTraq post for more information.
crontab in Vixie cron 4.1, when running with the -e option, allows local
users to read the cron files of other users by changing the file being
edited to a symlink. NOTE: there is insufficient information to know
whether this is a duplicate of CVE-2001-0235. See also this Security Focus
report.
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
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.
Three buffer overflows were discovered in xloadimage when handling the image title name. A malicious user can construct a NIFF file that when viewed and processed (with either zoom, reduce or rotate) by xloadimage, will cause the program to overwrite the return address and execute arbitrary code.
A buffer overflow has been discovered in the sendmail program of
xmail, an advanced, fast and reliable ESMTP/POP3 mail server that
could lead to the execution of arbitrary code with group mail
privileges.
The pixmap memory allocation code in the X.Org X window system is
vulnerable to an integer overflow, a local user can use this to
execute arbitrary code with elevated privileges.
A flaw was discovered in Xpdf in that could allow an attacker to construct
a carefully crafted PDF file that would cause Xpdf to consume all available
disk space in /tmp when opened.
