zoo Buffer Overflow in fullpath() Lets Remote Users Cause Arbitrary Code to Be Executed
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SecurityTracker Alert ID: 1015668
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SecurityTracker URL: http://securitytracker.com/id?1015668
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CVE Reference: CVE-2006-0855
(Links to External Site)
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Updated: Apr 4 2006
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Original Entry Date: Feb 23 2006
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Impact: Execution of arbitrary code via network, User access via network
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Description: A vulnerability was reported in zoo. A remote user can cause arbitrary code to be executed on the target user's system.
The fullpath() in 'misc.c' contains a buffer overflow. A remote user can create a specially crafted archive that, when processed
by the target user with zoo, will trigger a stack overflow and cause arbitrary code to be executed.
Jean-Sebastien Guay-Leroux
discovered this vulnerability.
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Impact: A remote user can create a specially crafted archive that, when processed by the target user with zoo, will cause arbitrary code to be executed. The code will run with the privileges of the target user.
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Solution: No vendor solution was available at the time of this entry.
An unofficial patch is available at:
http://archives.neohapsis.com/archives/fulldisclosure/2006-02/0568.html
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Cause: Boundary error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: Jean-Sebastien Guay-Leroux <jean-sebastien@guay-leroux.com>
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Message History:
None.
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Source Message Contents
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Date: Wed, 22 Feb 2006 22:54:58 -0500
From: =?ISO-8859-1?Q?Jean-S=E9bastien_Guay-Leroux?=
Subject: [Full-disclosure] zoo contains exploitable buffer overflows
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Topic: zoo contains exploitable buffer overflows
Announced: 2006-02-22
Product: zoo
Category: Applications/Archiving
Impact: Remote code execution
Credits: Jean-Sébastien Guay-Leroux
I. BACKGROUND
zoo is a file archiving utility for maintaining collections of files.
It uses Lempel-Ziv compression to provide space savings in the
range of 20 to 80 percent depending on the type of data. Written by
Rahul Dhesi, and posted to the USENET newsgroup comp.sources.misc.
II. PROBLEM DESCRIPTION
When feeding zoo a specially crafted archive, an attacker may be able
to trigger a stack overflow and seize control of the program.
fullpath()/misc.c accepts a pointer to a directory entry and returns the
combined directory name and filename. fullpath() calls the function
combine()/misc.c, and assume that the length of the string returned is never
longer than 256 bytes. In fact, the string returned can be made a little
longer than 512 bytes.
If the string is in fact longer than 256 bytes, a static variable can be
overflowed in the function fullpath()/misc.c . This string is later used
in a strcpy() on a destination buffer of 256 bytes on the stack.
It is then easy to overwrite EIP and take control of the program.
III. PATCH
diff -u -r -r zoo-2.10.old/misc.c zoo-2.10.orig/misc.c
--- zoo-2.10.old/misc.c 1991-07-05 12:00:00.000000000 -0400
+++ zoo-2.10.orig/misc.c 2006-01-29 17:20:35.000000000 -0500
@@ -135,11 +135,16 @@
char *fullpath (direntry)
struct direntry *direntry;
{
- static char result[PATHSIZE];
+ static char result[PATHSIZE+PATHSIZE+12]; // Room for enough space
combine (result,
direntry->dirlen != 0 ?
direntry->dirname : "",
(direntry->namlen != 0) ? direntry->lfname :
direntry->fname
);
+ if (strlen (result) >= PATHSIZE) {
+ prterror ('f', "Combined dirname and filename too long\n");
+ }
return (result);
}
IV. CREDITS
Bug found by Jean-Sébastien Guay-Leroux
To contact me, visit http://www.guay-leroux.com/
_______________________________________________
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