DataRescue Interactive Disassembler Pro Buffer Overflow Vulnerability

iDEFENSE Security Advisory 01.24.05
www.idefense.com/application/poi/display?id=189&type=vulnerabilities
January 24, 2005

I. BACKGROUND

DataRescue Inc.'s IDA Pro is a Windows or Linux hosted multi-processor
disassembler and debugger providing a multitude of features. More
information is available at:

    http://www.datarescue.com/idabase/

II. DESCRIPTION

Exploitation of a buffer overflow vulnerability in DataRescue Inc.'s
Interactive Disassembler Pro (IDA Pro) allows attackers to execute
arbitrary code under the context of the logged on user.

The problem specifically exists in the code responsible for parsing the
Portable Executable import directory. The import directory lists all the
symbols imported by the PE file and is stored as an array of data
structures. Each data structure contains the name of the imported
library and a list of function pointers, known as the Import Address
Table. A stack-based buffer overflow occurs when parsing long import
library names in the following snippet of assembly from ida.wll
(IDA Pro v4.7):

    0x100838BB LEA EDX, [EBP-30C]
    0x100838C1 PUSH DWORD PTR [EBP+8]
    0x100838C4 PUSH EDX
    0x100838C5 CALL ida.#835

"EBP+8" from above represents the attacker-supplied source buffer and
"EBP-30C" represents the static stack-based destination buffer of
approximately 800 bytes. The "ida_835" procedure performs an unchecked
string copy overwriting a stored return address and allowing an attacker
to redirect CPU flow to eventually execute arbitrary code.

III. ANALYSIS

Exploitation of the described vulnerability allows attackers to execute
arbitrary code under the context of the logged in user. Exploitation
requires that an attacker convince a target user to open a malicious
Portable Executable file with a vulnerable version of IDA Pro. IDA Pro
is the primary disassembler used by many security researchers. As such,
the severity of this issue is exacerbated when considering the impact of
a fast spreading worm combined with an exploit for this vulnerability.

Although simple modification of an import library name is sufficient to
exploit this vulnerability, the Windows loader will fail to recognize it
as a valid PE file. This will result in a non-executable malicious
binary. iDEFENSE has discovered a method for exploiting this
vulnerability in a fashion that is undetectable via PE import table
entry analysis, and that is affective against IDA Pro and will load and
execute as a regular binary without error.

It should be noted that other applications designed to analyze PE
executables may also be vulnerable. PEiD is a freely available PE
analysis tool and is also susceptible to attack.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in IDA Pro
versions 4.6 Service Pack 1 and 4.7 on both the Microsoft Windows and
Linux platforms. It is suspected that earlier versions are also
affected.

V. WORKAROUND

Prior to opening unknown files with vulnerable versions of IDA Pro,
examine the PE import table entries for long or abnormal strings. There
are a number of tools available for analyzing the PE file format. It is
important to note that this method will not catch all exploit vectors.

VI. VENDOR RESPONSE

"A temporary fix is available here

   http://www.datarescue.com/cgi-local/ultimatebb.cgi?/forum/2.html

A more generic fix will be available in the next IDA Pro release."

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2005-0115 to these issues. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

01/12/2005      Initial vendor notification
01/12/2005      Initial vendor response
01/24/2005      Coordinated public disclosure

IX. CREDIT

Lord Yup is credited with this discovery.

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

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
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part of this alert in any other medium other than electronically, please
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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.