Sun iPlanet Web Server Buffer Overflow in Encoded Transfer Chunk Processing Allows Remote Users to Execute Arbitrary Code With Root Privileges
SecurityTracker Alert ID: 1005000|
SecurityTracker URL: http://securitytracker.com/id/1005000
(Links to External Site)
Date: Aug 9 2002
Denial of service via network, Execution of arbitrary code via network, Root access via network|
Fix Available: Yes Vendor Confirmed: Yes Exploit Included: Yes |
Version(s): 4.1, 6.0|
A buffer overflow vulnerability was reported in Sun's iPlanet web server. A remote user can execute arbitrary code on the system and obtain root privileges or can cause the web service to crash.|
eEye Digital Security reported that there is a vulnerability in the processing of encoded transfer chunks. A remote user can send a specially crafted HTTP session to overwrite a portion of the heap and alter the flow of code execution to execute arbitrary code on the server. The bug is due to the incorrect calculation of message size.
According to the report, this is not the same as the integer overflow in transfer chunk encoding that was recently reported for Microsoft Internet Information Server and Apache web servers.
A demonstration exploit session is provided (where '[DATA]' will overflow heap memory):
POST /EEYE.html HTTP/1.1
A remote user can execute arbitrary code on the system with root privileges or can cause the service to crash.|
The vendor has released a fixed version (4.1 SP11 and 6.0 SP4), available at:|
Also, a patch is available at:
Vendor URL: www.sun.com/service/support/software/iplanet/alerts/transferencodingalert-23july2002.html (Links to External Site)
|Underlying OS: UNIX (Solaris - SunOS)|
Source Message Contents
Subject: [VulnWatch] EEYE: Sun(TM) ONE / iPlanet Web Server 4.1 and 6.0 Remote Buffer Overflow|
Sun(TM) ONE / iPlanet Web Server 4.1 and 6.0 Remote Buffer Overflow
Release Date: August 8, 2002
High (Remote SYSTEM/ROOT)
iPlanet 6.0 and prior
A vulnerability in transfer chunking can be exploited to remotely execute
code of an attacker's choice on a vulnerable machine. By sending a carefully
crafted session, an attacker can overwrite a section of the heap. Various
data structures in the overwritten heap can be manipulated to move attacker
supplied data to attacker supplied memory addresses, thereby altering the
flow of execution into an attacker supplied payload.
Note this variant is not the integer overflow affecting IIS and Apache that
was discovered during regression testing with Microsoft. This is another
variant relating to incorrect size calculation.
The following example will show the vulnerable condition:
POST /EEYE.html HTTP/1.1
[DATA] will overwrite heap memory. Increase or decrease depending on
The example session above overwrites a section of the heap that contains
data structures related to the Memory management system. By manipulating the
content of these structures, we can overwrite an arbitrary 4 bytes of memory
with an attacker supplied address.
It is widely assumed that the risk for these type of vulnerabilities is
fairly low due to the fact that addressing is dynamic and that you must use
brute force in your attack; however, this is false assumption and
exploitation can be successful with one attempt, across dll versions. An
attacker can overwrite static global variables, stored function pointers,
process management structures, memory management structures, or any number
of data types that will allow him to gain control of the target application
in one session.
Sun has released a security bulletin and patch:
Credit: Riley Hassell
Eli, Kasia, Halvar, FX, and the three amigos K2, Dark Spyrit, and Joey.
Copyright (c) 1998-2002 eEye Digital Security
Permission is hereby granted for the redistribution of this alert
electronically. It is not to be edited in any way without express consent of
eEye. If you wish to reprint the whole or any part of this alert in any
other medium excluding electronic medium, please e-mail alert@eEye.com for
The information within this paper may change without notice. Use of this
information constitutes acceptance for use in an AS IS condition. There are
NO warranties with regard to this information. In no event shall the author
be liable for any damages whatsoever arising out of or in connection with
the use or spread of this information. Any use of this information is at the
user's own risk.
Please send suggestions, updates, and comments to:
eEye Digital Security