Buffer-overflow and format string in White_Dune 0.29beta791 Jan 02 2008 07:55PM
Luigi Auriemma (aluigi autistici org)

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Luigi Auriemma

Application: White_Dune
http://vrml.cip.ica.uni-stuttgart.de/dune/
Versions: <= 0.29beta791
Platforms: Unix/Linux/MacOSX and Windows
Bugs: A] buffer-overflow in Scene::errorf
B] format string in ImportFile
Exploitation: local
Date: 02 Jan 2008
Author: Luigi Auriemma
e-mail: aluigi (at) autistici (dot) org [email concealed]
web: aluigi.org

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1) Introduction
2) Bugs
3) The Code
4) Fix

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===============
1) Introduction
===============

White_Dune is an open source editor/viewer for the VRML97 files.

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2) Bugs
=======

-----------------------------------
A] buffer-overflow in Scene::errorf
-----------------------------------

A buffer-overflow vulnerability is located in the function which builds
the error messages for the problems happened during the parsing of the
WRL file.

From Scene.cpp:

void
Scene::errorf(const char *fmt, ...)
{
va_list ap;
char buf[1024], buf2[1024];
const char *url = "";

va_start(ap, fmt);
vsprintf(buf, fmt, ap);
if (TheApp->getImportURL() != NULL)
url = TheApp->getImportURL();
mysnprintf(buf2, 1024, "%s %d: %s", url, lineno, buf);
_compileErrors += buf2;
}

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B] format string in ImportFile
------------------------------

Another problem related to the handling of the errors.
After the building of the error message the parse() function returns
immediately and swDebugf() is called for visualizing it to stderr or to
the debugger without using the needed format argument required by the
function.

From DuneApp.cpp:

DuneApp::ImportFile(const char *openpath, Scene* scene, bool protoLibrary,
Node *node, int field)
...
if (errors[0]) {
swMessageBox(_mainWnd, errors, "Parse Errors", SW_MB_OK, SW_MB_WARNING);
swDebugf(errors);
...

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===========
3) The Code
===========

http://aluigi.org/poc/whitedunboffs.zip

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======
4) Fix
======

Version 0.29beta795

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---
Luigi Auriemma
http://aluigi.org

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