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Date: Thu, 2 Apr 2015 08:55:33 +0100
From: "Nicholas Lemonias." <>
Subject: Security Audit Notes - OpenSSL v1.0.2a (latest) Issues - Advanced
 Information Security Corporation

-=[Advanced Information Security Corp]=-

Author: Nicholas Lemonias
Report Date: 2/4/2015

During a source-code audit of the OpenSSL v1.0.2a (Latest)
implementation for linux; conducted internally by the Advanced
Information Security
Group, instances of insecure function use were observed, which could
lead to a number of attacks.

 Software Overview
 OpenSSL is an open-source implementation of the SSL and TLS protocol.
 The core library is written in the C Language, and implements basic
 cryptographic functions, and
 also provides various utility functions. Implementation versions are
 available for most UNIX-like operating systems (including
 Solaris,Linux, Mac OS X and the various open-source BSD operating
 systems), OpenVMS and Microsoft Windows. IBM provides a port for the
 System i (OS/400). OpenSSL is based on SSLeay by Eric Andrew Young and
 Tim Hudson, development of which unofficially ended on December 17,
 1998, when Young and Hudson both started to work for RSA Security.

 PoC 1 - Code Snippet [CWE 362]

 out = vms_fopen(file, "rb+", VMS_OPEN_ATTRS);
    if (out == NULL)
        out = vms_fopen(file, "wb", VMS_OPEN_ATTRS);
    if (out == NULL)
        out = fopen(file, "wb");
    if (out == NULL)
        goto err;

#ifndef NO_CHMOD
    chmod(file, 0600);

Description: The calling function does not provide any security
validation controls, which would effectively prevent a race condition.
The use of open() with the right attributes was agreed.

PoC 2 - Code Snippet [CWE 690]

char *CRYPTO_strdup(const char *str, const char *file, int line)
char *ret = CRYPTO_malloc(strlen(str) + 1, file, line);

strcpy(ret, str);
return ret;

Description: The function call does not make sure that ret is not NULL.

PoC 3 - Code Snippet [CWE 134]

fprintf(stderr, (isprint(adata->contents[i])) ? "%c " : "%02x",

Description: The function call is prone to a format string attack.

Sincere Thanks to the OpenSSL team for their mutual efforts.


[1] Oracle (2015). Basic Library Functions - Title: fopen() man pages
section 3: Basic Library Functions [Online]
 Available at:
[Last Accessed 2 April, 2015]

[2] M. Howard, D. LeBlanc Writing Secure Code, Second Edition Microsoft Press

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