Bug 143051 - CAN-2004-1261 Bernstein class reports buffer overflow in asp2php
CAN-2004-1261 Bernstein class reports buffer overflow in asp2php
Product: Fedora
Classification: Fedora
Component: asp2php (Show other bugs)
All Linux
medium Severity low
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Assigned To: Joe Orton
Brian Brock
: Security
Depends On:
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Reported: 2004-12-15 18:58 EST by Alan Cox
Modified: 2007-11-30 17:10 EST (History)
0 users

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Doc Type: Bug Fix
Doc Text:
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Last Closed: 2005-03-02 14:36:15 EST
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Description Alan Cox 2004-12-15 18:58:08 EST


Qiao Zhang, a student in my Fall 2004 UNIX Security Holes course, has
discovered two remotely exploitable security holes in asp2php. I'm
publishing this notice, but all the discovery credits should be assigned
to Zhang.

You are at risk if you take an ASP script from an email message (or a
web page or any other source that could be controlled by an attacker)
and feed that script through asp2php. (The asp2php documentation does
not tell users to avoid taking input from the network.) Whoever provides
that script then has complete control over your account: she can read
and modify your files, watch the programs you're running, etc.

Proof of concept: On an x86 computer running FreeBSD 4.10, type

   wget http://downloads.mikekohn.net/asp2php/asp2php-0.76.23.tar.gz
   gunzip < asp2php-0.76.23.tar.gz | tar -xf -
   cd asp2php-0.76.23

to download and compile the asp2php program, version 0.76.23 (current).
Then save the file 29-1.asp attached to this message, and type

   ./asp2php 29-1.asp

with the unauthorized result that a file named EXPLOITED is created in
the current directory. 29-2.asp is similar but uses a separate buffer
overflow. (I tested these with a 541-byte environment, as reported by
printenv | wc -c.)

Both buffer overflows can be blamed on gettoken(), which has a
fundamentally broken gets()-style API. The preparse() function calls
gettoken() to read data into a 1024-byte token[] array, and to read data
into a 1024-byte temp[] array.
Comment 1 Josh Bressers 2004-12-16 08:06:02 EST
This issue also affects FC3
Comment 4 Joe Orton 2005-03-02 14:36:15 EST
Marking as WONTFIX; asp2php is not safe to run on "untrusted" input
code and requires a redesign to fix that.  The package has been
dropped from future releases of Fedora Core 4.

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