Paul Starzetz has discovered a
vulnerability in the Linux kernel that can be used to gain root access
to the system.
The vulnerability, published on May 11, affects the kernel's ELF
(Executable and Linking Format) loader, which could allow a local user to
use a manipulated binary to gain elevated privileges.
This vulnerability affects kernels in the 2.2, 2.4 and 2.6
series. According to Starzetz report, the flaw is in the function
elf_core_dump(), in binfmt_elf.c.
This function does not correctly handle the argument area
of the ELF process, which could be abused to override the memory layout:
It is possible to create a manipulated ELF binary, that specifies an ELF
program section to be loaded at the place of program arguments, but with no
access rights itself (that is, a page table level protection equal to
PROT_NONE). That will cause the strnlen_user() function to page fault at
the first attempt to count argument lengths. Moreover, the loading of
ELF sections happens just after the initial arguments have been set up in
the fresh memory space, so that it is easily possible to "override" the
predefined ELF memory layout. To illustrate this, here two memory
layouts:
(1) initial ELF memory layout before starting to load program sections:
----------------EMPTY------------------[ ARGS stack region ] TASK_SIZE
(2) possible memory layout after loading ELF sections:
---------[CODE][DATA]------------------[FAKE][stack region ] TASK_SIZE
where FAKE is an ELF section mmaped into memory with PROT_NONE rights
specified.
To date, only Trustix has
issued an alert and fix for this issue. Red Hat has just issued a kernel update,
but the ELF vulnerability is not mentioned in
the release announcement. We've checked the lists for Ubuntu, Debian,
Mandriva, Slackware, Fedora, Fedora Legacy, Yellow Dog -- none of these
distributions have issued a update yet for what appears to be a fairly
serious local exploit. As of this writing, nearly a week has passed since
Starzetz made the discovery public.
At the same time, most of those vendors have released new versions of Squid
to deal with a vulnerability
that would allow malicious users to spoof DNS lookups. The Squid
vulnerability was announced the same day as the ELF loader vulnerability.
It does seem that a patch, at least for the 2.6 series, is
available. Given the potential severity of the vulnerability, we're
curious to see how long it will be before updates are made available from
the major distributions. With Linux under close scrutiny for security
vulnerabilities and vendor response times, one hopes that it will be soon.
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.
Primoz Bratanic discovered that the sql_escape_func function of FreeRADIUS
1.0.2 and earlier may be vulnerable to a buffer overflow. He also
discovered that FreeRADIUS fails to sanitize user-input before using it in
a SQL query, possibly allowing SQL command injection.
The extended attribute code (at least as backported by Red Hat into the 2.4 kernel) suffers from an offset handling error which can be exploited to cause a system crash.
Several vulnerabilities
in the Mozilla Suite (versions before 1.7.8) and Firefox (versions before
1.0.4) allow an attacker to conduct cross-site scripting attacks or to
execute arbitrary code.
Josh Bressers discovered a buffer overflow in the ieee_putascii()
function of nasm 0.98 and earlier. If an attacker tricked a user into
assembling a malicious source file, they could exploit this to execute
arbitrary code with the privileges of the user that runs nasm.
Paul Laudanski reported a
vulnerability in phpBB (in versions prior to 2.0.15) in the processing
of BBCode. A remote user may be able to cause scripting code to be executed
by the target user.
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.
Multiple stack-based buffer overflows in libcURL and cURL 7.12.1, and
possibly other versions, allow remote malicious web servers to execute
arbitrary code via base64 encoded replies that exceed the intended buffer
lengths when decoded.
CVS (in version prior to 1.11.20) has one or more buffer overflow vulnerabilities, memory leaks, and a NULL pointer dereferencing error.
These can be used to launch a remote denial of service or to remotely
execute arbitrary code.
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.
Dnsmasq does not properly detect that DNS replies received do not
correspond to any DNS query that was sent. Rob Holland of the Gentoo Linux
Security Audit team also discovered two off-by-one buffer overflows that
could crash DHCP lease files parsing.
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.
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.
Max Vozeler discovered an integer overflow in camel-lock-helper. A
user-supplied length value was not validated, so that a value of -1
caused a buffer allocation of 0 bytes; this buffer was then filled by
an arbitrary amount of user-supplied data. A local attacker or a malicious
POP3 server could exploit this to execute arbitrary code with root
privileges (because camel-lock-helper is installed as setuid root).
The Firefox browser (and Mozilla as well) suffers from several vulnerabilities which can be exploited by a remote attacker to execute arbitrary code. See this advisory for a discussion of the worst two. Upgrading to version 1.0.4 will fix the problems.
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.
Jean-Yves Lefort discovered a buffer overflow in the
gaim_markup_strip_html() function. This caused Gaim to crash when
receiving certain malformed HTML messages. (CAN-2005-0965)
Jean-Yves Lefort also noticed that many functions that handle IRC
commands do not escape received HTML metacharacters; this allowed
remote attackers to cause a Denial of Service by injecting arbitrary
HTML code into the conversation window, popping up arbitrarily many
empty dialog boxes, or even causing Gaim to crash. (CAN-2005-0966)
Gaim contains buffer overflows in its handling of URLs and MSN messages. By sending malicious messages, a remote attacker could exploit these overflows and execute arbitrary code.
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.
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.
The catchsegv script in the glibc package has a symlink vulnerability
that may allow a local user to overwrite arbitrary
files with the permissions of the user that is running the script.
GnuPG (and other PGP-like systems) suffers from an information leak which could, in some situations, be used by an attacker to obtain plain text from an encrypted message. See this message for a detailed explanation of the problem. "We know of no real-world application that is affected by this type of attack. It is an attack that requires the active participation of someone who holds the actual key required to decrypt a message. Thus, it is not something you are likely to see."
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.
gzip suffers from a race condition which could allow a fast-fingered attacker to change the permissions on files owned by others. There is also a directory traversal vulnerability associated with the -N option.
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.
Tavis Ormandy of the Gentoo Linux Security Team discovered an integer
overflow in the ELF parser, leading to a heap-based buffer overflow.
The vendor has reported that an unrelated buffer overflow has been
discovered in the PE parser. Successful exploitation would require the
victim to open a specially crafted file using HT, potentially permitting an
attacker to execute arbitrary code.
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.
InfoZip reports that Zip 2.3 and
(presumably) all previous versions have a buffer-overrun vulnerability
relating to deep directory paths that could potentially lead to local
privilege escalation (e.g., in the case of automated, Zip-based backups).
All versions of UnZip through 5.50 have a number of directory-traversal
vulnerabilities.
Thiago Macieira discovered a vulnerability in the kioslave library,
which is part of kdelibs, which allows a remote attacker to execute
arbitrary FTP commands via an ftp:// URL that contains an URL-encoded
newline before the FTP command.
Paul Starzetz has posted an
advisory for yet another kernel vulnerability.
In this case, by using a specially manipulated ELF binary, a local attacker
can compromise the system (via the core dump code) and obtain root access.
This vulnerability affects all kernels from 2.2 through 2.6.12-rc4.
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.
KDE has issued a security advisory for
kimgio. This is found in kdelibs as shipped with KDE 3.2 up to including
KDE 3.4. kimgio contains a PCX image file format reader that does not
properly perform input validation. A source code audit performed by the KDE
security team discovered several vulnerabilities in the PCX and other image
file format readers, some of them exploitable to execute arbitrary code.
KDE has issued a security advisory for
Kommander. Quanta 3.1.x, KDE 3.2 and new up to including KDE 3.4.0 are
vulnerable. Kommander executes without user confirmation data files from
possibly untrusted locations. As they contain scripts, the user might
accidentally run 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.
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.
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.
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.
Trustix Secure Linux discovered a vulnerability in a supplemental script of
the lvm10 package. The program "lvmcreate_initrd" created a temporary
directory in an insecure way, which could allow a symlink attack to create
or overwrite arbitrary files with the privileges of the user invoking the
program.
The "private" module in the mailman mailing list manager fails to sanitize path names adequately. An attacker could exploit this vulnerability to retrieve private information, including passwords and private list archives.
A security audit of the MediaWiki project discovered that MediaWiki is
vulnerable to several cross-site scripting and cross-site request
forgery attacks, and that the image deletion code does not sufficiently
sanitize input parameters.
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 following vulnerabilities were found and fixed in the Mozilla Suite
and Mozilla Firefox:
Vladimir V. Perepelitsa reported a memory disclosure bug in
JavaScript's regular expression string replacement when using an
anonymous function as the replacement argument (CAN-2005-0989).
moz_bug_r_a4 discovered that Chrome UI code was overly trusting DOM
nodes from the content window, allowing privilege escalation via DOM
property overrides.
Michael Krax reported a possibility to run JavaScript code with
elevated privileges through the use of javascript: favicons.
Michael Krax also discovered that malicious Search plugins could
run JavaScript in the context of the displayed page or stealthily
replace existing search plugins.
shutdown discovered a technique to pollute the global scope of a
window in a way that persists from page to page.
Doron Rosenberg discovered a possibility to run JavaScript with
elevated privileges when the user asks to "Show" a blocked popup that
contains a JavaScript URL.
Finally, Georgi Guninski reported missing Install object instance
checks in the native implementations of XPInstall-related JavaScript
objects.
The following Firefox-specific vulnerabilities have also been
discovered:
Kohei Yoshino discovered a new way to abuse the sidebar panel to
execute JavaScript with elevated privileges.
Omar Khan reported that the Plugin Finder Service can be tricked to
open javascript: URLs with elevated privileges.
Heap overflows have been found in the code handling RealMedia RTSP and
Microsoft Media Services streams over TCP (MMST). By setting up a
malicious server and enticing a user to use its streaming data, a remote
attacker could possibly execute arbitrary code on the client computer with
the permissions of the user running MPlayer.
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).
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.
A format string flaw has been detected in the my_xlog() function of the
Oops! proxy (in versions prior to 1.5.23), which is called by the
passwd_mysql and passwd_pgsql module's auth() functions.
OpenOffice.org suffers from a buffer overflow in the parsing code for MS Word files; see this advisory for details. Since this vulnerability could conceivably be exploited via files received in email messages, it should be taken seriously.
The der_chop script in openssl has a temp file vulnerability that may allow
an attacker to overwrite arbitrary files with the permissions that
the script is running under.
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.
The php4 EXIF module has two vulnerabilities. An
integer overflow in the exif_process_IFD_TAG() function
can be exploited to cause a buffer overflow for the
purpose of arbitrary code execution.
EXIF headers with a large IFD nesting level can be used
to cause a denial of service. Remote exploits are possible.
Two DoS vulnerabilities exist in PHP versions 4.2.2, 4.3.9, 4.3.10 and
5.0.3. One in the php_handle_iff function in image.c allows remote
attackers to cause a denial of service (infinite loop) via a -8 size
value. The php_next_marker function in image.c allows remote attackers to
cause a denial of service (infinite loop) via a JPEG image with an invalid
marker value, which causes a negative length value to be passed to
php_stream_seek. This later vulnerability also exists in PHP 3.
postgresql has a vulnerability in which the EXECUTE privilege may
not be checked on custom functions. This may allow any database user to
circumvent the EXECUTE restriction on functions.
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.
RealNetworks, Inc. has fixed a
security vulnerability that offered the potential for an attacker to
run arbitrary or malicious code on a customer's machine. Linux RealPlayer
10 (10.0.0 - 3) and Helix Player (10.0.0 - 3) are vulnerable.
Max Vozeler discovered a vulnerability in pppoe, the PPP over Ethernet
driver from Roaring Penguin. When the program is running setuid root
(which is not the case in a default Debian installation), an attacker
could overwrite any file on the file system.
The upstream developers of Ruby have corrected a problem in the CGI
module for this language. Specially crafted requests could cause an
infinite loop and thus cause the program to eat up cpu cycles.
A buffer overflow has been discovered in Smail 3.2.0.120, an electronic
mail transport system, which allows remote attackers and local users to
execute arbitrary code.
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.
Squid 2.5.STABLE9 and earlier does not trigger a fatal error when it
identifies missing or invalid ACLs in the http_access configuration, which
could lead to less restrictive ACLs than intended by the administrator.
Versions of sudo prior to 1.6.8p2 fail to properly sanitize the environment prior to running shell scripts; this failure can be exploited by a sudo user to subvert scripts and obtain shell access. See the 1.6.8p2 announcement 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.
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)
Two buffer overflow flaws were discovered in the way the telnet client
handles messages from a server. An attacker may be able to execute
arbitrary code on a victim's machine if the victim can be tricked into
connecting to a malicious telnet server.
Ulf Harnhammar discovered that UnAce suffers from buffer overflows when
testing, unpacking or listing specially crafted ACE archives
(CAN-2005-0160). He also found out that UnAce is vulnerable to
directory traversal attacks, if an archive contains "./.." sequences or
absolute filenames (CAN-2005-0161).
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.
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.
Heap overflows have been found in the code handling RealMedia RTSP and
Microsoft Media Services streams over TCP (MMST). See Xine Advisory
XSA-2004-8 for details.
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.
Greg Roelofs has reported multiple input validation errors in XV image
decoders. Tavis Ormandy of the Gentoo Linux Security Audit Team has
reported insufficient validation in the PDS (Planetary Data System)
image decoder, format string vulnerabilities in the TIFF and PDS
decoders, and insufficient protection from shell meta-characters in
malformed filenames. Successful exploitation would require a victim to
view a specially created image file using XV, potentially resulting in the
execution of arbitrary code.
