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Category:   Application (E-mail Server)  >   GNU Mailutils Vendors:   GNU [multiple authors]
GNU Mailutils Buffer Overflow and Format String Bugs Let Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1014052
SecurityTracker URL:  http://securitytracker.com/id/1014052
CVE Reference:   CVE-2005-1520, CVE-2005-1521, CVE-2005-1522, CVE-2005-1523   (Links to External Site)
Date:  May 25 2005
Impact:   Denial of service via network, Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 0.5, 0.6
Description:   iDEFENSE reported several vulnerabilities in GNU Mailutils. A remote user can execute arbitrary code on the target system. A remote authenticated user can deny service.

The header_get_field_name() function in 'mailbox/header.c' (part of the mail client application) contains a buffer overflow [CVE: CVE-2005-1520]. A remote user can send specially crafted e-mail message to a target user to trigger the overflow and execute code with the privileges of the target user.

The fetch_io() function in the imap4d server contains an integer overflow [CVE: CVE-2005-1521]. A remote authenticated user can send a specially crafted 'END' parameter value to trigger the overflow and execute arbitrary code with the privileges of the 'daemon' user.

The imap4d server does not properly validate user-supplied input in the FETCH command [CVE: CVE-2005-1522]. A remote authenticated user can supply a specially crafted sequence range argument (such as 1:4294967294) to cause a server process to enter an infinite loop and allocating increasing amounts of memory, resulting in denial of service conditions.

The imap4d server contains a format string flaw in the processing of the user-supplied command tag [CVE: CVE-2005-1523]. A remote user can send a specially crafted command tag value to trigger the flaw and execute arbitrary code on the target system. Code will run with the privileges of the 'daemon' user.

The vendor was notified on May 12, 2005.

infamous41md@hotpop.com discovered this vulnerability.

Impact:   A remote user can execute arbitrary code on the target system.

A remote authenticated user can cause denial of service conditions.

Solution:   The vendor has released a fixed version (0.6.90), available at:

ftp://alpha.gnu.org/gnu/mailutils/

Vendor URL:  www.gnu.org/software/mailutils/mailutils.html (Links to External Site)
Cause:   Boundary error, Input validation error, State error
Underlying OS:  Linux (Any), UNIX (Any)

Message History:   None.


 Source Message Contents

Subject:  iDEFENSE Security Advisory 05.25.05: GNU Mailutils 0.6 mail


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@hotpop.com is credited with the discovery of this
vulnerability.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

Free tools, research and upcoming events
http://labs.idefense.com

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
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

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.




GNU Mailutils 0.6 imap4d fetch_io Heap 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

Remote exploitation of an integer overflow in the fetch_io
function of the imap4d server from the GNU Project's Mailutils
package error may allow an authenticated remote attacker to 
execute arbitrary code.

The imap4d server allows remote users to retrieve their email
via the Internet Message Access Protocol, version 4rev1 as
specified in RFC3501. This is a client/server protocol supported
by a large number of email clients on multiple platforms.

The vulnerability specifically exists in the handling of partial
message requests. By supplying a value for the 'END' parameter
equal to 2 less than the largest value an integer on the
affected system can hold, it is possible to cause the server to
allocate a much smaller chunk of memory. An overflow can occur
when this memory chunk is referenced.

III. ANALYSIS

Successful exploitation of this vulnerability could allow a
remote authenticated used execute arbitrary commands in the
context of the 'daemon' user. As the service is forked from a
parent process, it would be possible for a remote attacker to
attempt to exploit this vulnerability multiple times, although
each failed attempt which caused a crash would be logged.

IV. DETECTION

iDEFENSE Labs has verified the existance of this vulnerability
in versions 0.5 and 0.6 of the GNU Mailutils package. It is
suspected that any previous versions which contain the imap4d
server are also affected.

V. WORKAROUND

iDEFENSE is currently unaware of any effective workarounds for
this issue. Access to the affected host should be filtered at
the network boundary if global accessibility is not required.
Restricting access to only trusted hosts and networks may reduce
the likelihood of exploitation.

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-2005-1521 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@hotpop.com is credited with the discovery of this
vulnerability.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

Free tools, research and upcoming events
http://labs.idefense.com

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
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

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.



GNU Mailutils 0.6 imap4d FETCH Commad Resource Consumption DoS
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

Remote exploitation of an input validation in the FETCH command
of the imap4d server from the GNU Project's Mailutils package
error may allow an authenticated remote attacker to perform a
denial of service against an affected system.

The imap4d server allows remote users to retrieve their email
via the Internet Message Access Protocol, Version 4rev1 as
specified in RFC3501. This is a client/server protocol supported
by a large number of email clients on multiple platforms.

The vulnerability specifically exists in the handling of the
sequence range agument to the FETCH command. A sequence range
such as 1:4294967294 will cause the the spawned instance of the
server to enter what is effectively an infinite loop, allocating
memory on each cycle.

III. ANALYSIS

Successful exploitation of the vulnerability would allow a
remote authenticated used to cause the system hosting the imap4d
to become unresponsive due to lack of memory resources. On some
operating systems, such as Linux, processes will be killed by
the kernel out of memory manager.

IV. DETECTION

iDEFENSE Labs has verified the existance of this vulnerability
in versions 0.5 and 0.6 of the GNU Mailutils package. It is
suspected that any previous versions which contain the imap4d
server are also affected.

V. WORKAROUND

iDEFENSE is currently unaware of any effective workarounds for
this issue. Access to the affected host should be filtered at
the network boundary if global accessibility is not required.
Restricting access to only trusted hosts and networks may reduce
the likelihood of exploitation.

Applying resource limits on the memory avaialable to the imap4d
process will cause the spawned instance of the server to exit
when it reaches the limit. Information on how to to perform this
operation is operating system dependant, and may cause some
normal operations, especially on large messages, to fail.

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-2005-1522 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@hotpop.com is credited with the discovery of this
vulnerability.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

Free tools, research and upcoming events
http://labs.idefense.com

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
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

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.





GNU Mailutils 0.6 imap4d Format String 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

Remote exploitation of a format string vulnerability in the
imap4d server within version 0.6 of the GNU Project's Mailutils
package could allow an unauthenticated attacker to execute
arbitrary code.

The imap4d server allows remote users to retrieve their email
via the Internet Message Access Protocol, Version 4rev1 as
specified in RFC3501. This is a client/server protocol supported
by a large number of email clients on multiple platforms.

The vulnerability specifically exists in the handling of the
command tag supplied by the remote user. Each client command
sent to the server is prefixed with an identifier which is
typically a short alphanumeric string such as "A0001". A
different tag is generated by the client for each command.  When
the server has completed the task, with either success or
failure, the server will send a reply with the same tag.

The following snippet of code shows some of the vulnerable code:

  asprintf (&tempbuf, "%s %s%s %s\r\n", command->tag, sc2string (rc),
            command->name, format);
  va_start (ap, format);
  vasprintf (&buf, tempbuf, ap);

The asprintf() command allocates a new string, created by
joining the values of the tag supplied by the remote user, the
text version of the result code, the name of the command being
executed, and the original format string supplied to this
function.

The effect of this line is to generate a new format string
string which is used to generate the output. As there is no
check for format specifiers in the user supplied input, a
remotely exploitable condition occurs.

III. ANALYSIS

Successful exploitation allows remote unauthenticated attackers
to execute arbitrary commands on an affected system as the
'daemon' user.

Sending the following command to an affected server will cause
the current connection to die when the fork()ed instance of the
server crashes:

%n%n%n%n%n die.

The '%n' format specifier writes the number of characters in the
output string generated so far to the memory address pointed at
by the current argument. In this case, the process attempts to
write the value 0 to the next 5 memory locations in the argument
list. As some of these arguments are not valid pointers, the
server dies attempting to write to an invalid memory location. 
This will not cause a denial of service, as a new instance of
the server is spawned for each accepted connection.

Information about the values on the stack below the current
position can be gained by sending a string similar to:

%p-%p-%p-%p-%p-%p-%p-%p-%p-%p-%p info

Using these format specifiers it is posslbe to contrstruct a
sequence of commands which will cause arbitrary values to be
written to arbitrary locations, allowing the execution of
arbitrary code.

IV. DETECTION

iDEFENSE Labs has verified the existance of this vulnerability
in versions 0.5 and 0.6 of the GNU Mailutils package. It is
suspected that any previous versions which contain the imap4d
server are also affected.

V. WORKAROUND

iDEFENSE is currently unaware of any effective workarounds for
this issue.  Access to the affected host should be filtered at
the network boundary if global accessibility is not required.
Restricting access to only trusted hosts and networks may reduce
the likelihood of exploitation.

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-2005-1523 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@hotpop.com is credited with the discovery of this
vulnerability.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

Free tools, research and upcoming events
http://labs.idefense.com

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
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

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.
 
 


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