[Full-disclosure] PHPCaptcha / Securimage 2.0.2 - Authentication Bypass - SOS-11-007
- From: "Lists" <lists@xxxxxxxxxxxxxxxxxxx>
- Date: Fri, 20 May 2011 19:06:02 +1000
Sense of Security - Security Advisory - SOS-11-007
Release Date. 20-May-2011
Last Update. -
Vendor Notification Date. 04-Apr-2011
Product. Securimage / PHPCaptcha
Affected versions. 1.0.4 - 2.0.2
Severity Rating. Medium
Impact. Authentication bypass
Attack Vector. Remote without authentication
Solution Status. Vendor workaround
CVE reference. Not yet assigned
PHPCaptcha, also known as Securimage, is a popular Open Source PHP
CAPTCHA library. It is also used in popular WordPress plugins such as
the 'Fast Secure Contact Form'. Insufficient distortion in the audio
version of the CAPTCHA allows an attacker to quickly decode the CAPTCHA
by performing basic binary analysis of the generated audio file. The
issue is compounded by the fact that even if the audio feature of the
CAPTCHA has been disabled, it can still be accessed by forceful
browsing to the /secure_play.php URI.
Proof of Concept.
Proof of concept code that works against the example_form.php page and
the MP3 file format provided with the standard PHPCaptcha package
available from www.phpcaptcha.org is available at:
Proof of concept code is only available for the MP3 version of the
audio, however the WAV audio format is also affected by the same
Remove the script securimage_play.php and disable the use of the Audio
Phil Taylor from Sense of Security Labs.
Sense of Security is a leading provider of information security and
risk management solutions. Our team has expert skills in assessment
and assurance, strategy and architecture, and deployment through to
ongoing management. We are Australia's premier application penetration
testing firm and trusted IT security advisor to many of the country's
Sense of Security Pty Ltd
Level 8, 66 King St
Sydney NSW 2000
T: +61 (0)2 9290 4444
F: +61 (0)2 9290 4455
The latest version of this advisory can be found at:
Other Sense of Security advisories can be found at:
Full-Disclosure - We believe in it.
Hosted and sponsored by Secunia - http://secunia.com/
- Prev by Date: Re: [Full-disclosure] New DDoS attack vector
- Next by Date: [Full-disclosure] Released FTP Password Decryptor !
- Previous by thread: [Full-disclosure] [SECURITY] [DSA 2238-1] vino security update
- Next by thread: [Full-disclosure] Released FTP Password Decryptor !