BugTraq
Denial-of-Service Vulnerability in IDA Pro Jun 28 2010 10:54AM
jason ngssoftware com
Denial-of-Service Vulnerability in IDA Pro

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June 28th, 2010

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Summary

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Name: Denial-of-Service Vulnerability in IDA Pro

Release Date: June 28th, 2010

Discoverer: Jason Geffner

Version Affected: IDA Pro 3.76 through 5.6

Risk: Low

Status: Published

============

Introduction

============

This paper discusses how a binary file could be crafted to cause IDA Pro to

consume 100% of CPU resources while trying to analyze it, thus preventing

disassembling. While this vulnerability is in the QNX file loader, a functional

COM file could be crafted to masquerade as a QNX file and trigger this issue.

This vulnerability was responsibly disclosed to IDA Pro's support personnel and

this advisory was not released until a fixed build was publicly released.

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Background

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"The IDA Pro Disassembler and Debugger is an interactive, programmable,

extendible, multi-processor disassembler hosted on Windows, Linux, or Mac OS X.

IDA Pro has become the de-facto standard for the analysis of hostile code,

vulnerability research and COTS validation." [1]

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Timeline

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07/28/98 IDA Pro loader for QNX files written

12/31/09 Denial-of-service vulnerability discovered in IDA Pro loader for QNX

files

12/31/09 Detailed vulnerability report responsibly disclosed to IDA Pro's

support personnel

01/04/10 Response received from IDA Pro's support personnel, confirming

vulnerability

06/25/10 IDA Pro 5.7 released, fixing vulnerability

06/28/10 Advisory released

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Vulnerability

=============

IDA Pro uses different file loaders to disassemble files of different formats

(PE, ELF, etc.). The loader for QNX files contains a vulnerability that allows

a specially crafted file to cause the loader to go into an infinite loop,

thereby consuming 100% of CPU resources and preventing disassembly.

The for-loop below is designed to iterate through each lmf_data structure in

the input file, advancing the file pointer based on sizeof(lmf_data) +

lmf_data.offset). However, if lmf_data.offset == -sizeof(lmf_data) then at is

never increased and this code will run in an infinite loop.

From \ldr\qnx\qnx.cpp(50):

for(uint32 at = sizeof(ex.lmf_header)+ex.lmf_header.data_nbytes;

lmf_data.segment_index != _LMF_EOF_REC;

at += sizeof(lmf_data) + lmf_data.offset)

{

qlseek( li, at, 0 );

if ( sizeof(_lmf_data) !=

qlread( li, &lmf_data, sizeof(_lmf_data) ) ) return 0;

switch(lmf_data.segment_index)

{

...

case _LMF_COMMENT_REC:

break;

...

}

}

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Exploit

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While this vulnerability is in the QNX file loader, a functional COM file could

be crafted to masquerade as a QNX file and trigger this issue. As such, it

would be possible for a malware author to create a working malicious COM

program, craft it to appear as a QNX file to IDA Pro, and thus prevent IDA Pro

from being able to disassemble it. Windows 7 will correctly run such a COM

program even if it is named with a .EXE extension.

See below for a proof-of-concept COM file. When run from a command-prompt, this

program will print, "I can't be opened in IDA Pro :)". When opened in IDA Pro,

it will cause IDA Pro to spin in an infinite loop.

00000000: 00 00 34 00 00 00 b4 09 eb 02 82 01 ba 13 01 cd ..4.............

00000010: 21 cd 20 49 20 63 61 6e 27 74 20 62 65 20 6f 70 !. I can't be op

00000020: 65 6e 65 64 20 69 6e 20 49 44 41 20 50 72 6f 20 ened in IDA Pro

00000030: 3a 29 24 00 00 00 00 00 00 00 01 00 fa ff ff ff :)$.............

00000040: 00 00 00 00 00 00 ......

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Conclusion

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In-depth code reviews and fuzzing should be performed on all software,

especially when the software is designed for analyzing malicious and/or

untrusted data.

===============

Fix Information

===============

This issue has now been resolved. IDA Pro 5.7 can be downloaded from

https://www.hex-rays.com/updida.shtml

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References

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[1] http://hex-rays.com/idapro/overview.htm

NGSSoftware Insight Security Research

http://www.ngssoftware.com/

http://www.databasesecurity.com/

http://www.nextgenss.com/

+44(0)208 401 0070

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