The CAPTCHA functionality in php-Nuke 6.0 through 7.9 uses fixed challenge/response pairs that only vary once per day based on the User Agent (HTTP_USER_AGENT), which allows remote attackers to bypass CAPTCHA controls by fixing the User Agent, performing a valid challenge/response, then replaying that pair in the random_num and gfx_check parameters.
CVSS Severity (version 2.0):
Impact Subscore: 6.4
Exploitability Subscore: 10.0
CVSS Version 2 Metrics:
Access Vector: Network exploitable
Access Complexity: Low
Authentication: Not required to exploit
Impact Type: Allows unauthorized disclosure of information; Allows unauthorized modification; Allows disruption of service
References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving NIST webspace. We have provided these links to other web sites because
they may have information that would be of interest to you. No inferences should be drawn on account of other sites
being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose.
NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further,
NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about
this page to email@example.com.
20060218 [waraxe-2006-SA#045] - Bypassing CAPTCHA in phpNuke 6.x-7.9