iDEFENSE Security Advisory 05.25.05: GNU Mailutils 0.6 mail header_get_field_name() Buffer Overflow Vulnerability
GNU Mailutils 0.6 mail header_get_field_name() Buffer Overflow
Vulnerability
iDEFENSE Security Advisory 05.25.05
http://www.idefense.com/application/poi/display?type=vulnerabilities
May 25, 2005
I. BACKGROUND
The GNU mailutils package is a collection of mail-related
utilities, including local and remote mailbox access services.
More information is available at the following site:
http://www.gnu.org/software/mailutils/mailutils.html
II. DESCRIPTION
Exploitation of a buffer overflow vulnerability in the mail
binary of the GNU Projects Mailutils package may allow a remote
attacker to execute commands with the privileges of the
targeted user.
Due to a coding error in the library function
header_get_field_name() in mailbox/header.c, a buffer overflow
condition exists. The code below checks if the value of 'len' is
greater than the value of 'buflen', but always sets the value of
'len' to be the same, effectively performing no instruction.
len = (len > buflen) ? len : len;
This code will set 'len' to the value of 'buflen' if 'len' is
greater than 'buflen'. This typo allows the buffer overflow to
occur. The code should be:
len = (len > buflen) ? buflen : len;
III. ANALYSIS
Successful exploitation of the vulnerability would allow an
email sent by a remote user to cause a buffer overflow, allowing
execution of arbitrary commands in the context of the targeted
user. Access to a user account may allow further escalation of
privileges via local attacks.
IV. DETECTION
iDEFENSE Labs has verified the existence of this vulnerability
in versions 0.5 and 0.6 of the GNU Mailutils package. It is
suspected that any previous versions may also be affected.
It should be noted that the mail command from the GNU mailutils
package is NOT the default mail client on the vast majority of
Linux installations. The mailx mail client is by far much more
likely to be installed. The mailx mail client is typically
installed in /bin/mail, whereas the GNU mailutils mail client is
typically installed in /usr/bin/mail. These values are not
universal, and additional verification should be performed to
determine which version you have installed.
V. WORKAROUND
When possible, run client software as a regular user with
limited access to system resources. This may limit the immediate
consequences of client-side vulnerabilities.
VI. VENDOR RESPONSE
This vulnerability has been fixed in GNU mailutils 0.6.90 which is
available for download at:
ftp://alpha.gnu.org/gnu/mailutils/
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1520 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
05/12/2005 Initial vendor notification
05/12/2005 Initial vendor response
05/25/2005 Public disclosure
IX. CREDIT
infamous41md@xxxxxxxxxx is credited with the discovery of this
vulnerability.
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X. LEGAL NOTICES
Copyright (c) 2005 iDEFENSE, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.