You have lots of good points. Thank you again.

I work for AOL, developing cross platform SDK for instant messaging that
supports plugins. Plugins can be malicious. And AOL is responsible for
protecting users' identity and privacy. Considering our user base, a
trojan is more likely to target our users than to protect them. 

What do the majority applications do on Unix if static linking with
openssl isn't suitable?

Thanks.

Yvonne
 

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of David Schwartz
Sent: Friday, April 18, 2008 6:29 PM
To: openssl-users@openssl.org
Subject: RE: Openssl loading


> Thanks for your response. Shipping my own version of openssl is ruled 
> out. So I have to trust the system installed one. Think at least on 
> some Unix systems, LD_LIBRARY_PATH is searched first.

Right, this is beause:

1) A library cannot do any harm the user could not do directly. So
there's no point in preventing him from replacing system libraries.

2) The user may need to replace a system library for a given application
for various reasons, including if the system library has a bug that
other programs rely on.

> I worry Trojan horses
> hidden there. I am advised to zeroing-out this env variable before 
> loading openssl.

I would not advise this. At least as likely as a trojan is that the
system-installed one has a problem and the user has installed a fixed
OpenSSL build. The trojan can just as easily intercept your programs
file operations to redirect the attempt to link to the system-installed
OpenSSL to be to a user-provided one.

> What else I can do?

Consider very carefully whether protecting the user from himself is
worth preventing him from protecting himself.

It's very hard to give you advice without having any understanding of
what your threat model is. For example, if your program is designed to
protect banking transactions, that's a very different threat model from
if your program is designed to protect its own licensing.

DS


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