oss-sec mailing list archives
Re: CVE Request -- Data-FormValidator -- Reports invalid field as valid when untaint_all_constraints used
From: Mark Stosberg <mark () summersault com>
Date: Mon, 13 Jun 2011 10:57:36 -0400
On 06/12/2011 10:49 AM, Jan Lieskovsky wrote:
Hello, Josh, Steve, vendors, It was found that perl-Data-FormValidator, a HTML form user input validator, used to treat certain invalid fields as valid, when the untaint_all_constraints directive was used (default for majority of Data-FormValidator routines). A remote attacker could use this flaw to bypass perl Taint mode protection mechanism via specially-crafted input provided to the HTML form. Note: Hopefully Damyan, Mark can clarify here, if valid data from Data-FormValidator are automatically marked as untainted for perl Taint mode or not. If there still is perl Taint mode protection check present, even on valid Data-FormValidator data and it couldn't happen, that tainted data would be passed further to the script processing, then this is not a security issue.
I maintain DFV and have looked at this now. The issue was limited to fields whose constraints were defined as regular expressions. To trigger it, it was also required that a unrelated Regex match before the particular field validation happened was successful. In that case, a value could be marked as "valid" when it was invalid, and would also be untainted. I've reviewed a test and fix for this now and am ready to release it. If there is a CVE number about to be assigned, I can wait for that. Thanks for bringing this to my attention. Mark
Current thread:
- CVE Request -- Data-FormValidator -- Reports invalid field as valid when untaint_all_constraints used Jan Lieskovsky (Jun 12)
- Bug#629511: Info received (CVE Request -- Data-FormValidator -- Reports invalid field as valid when untaint_all_constraints used) Debian Bug Tracking System (Jun 12)
- Re: CVE Request -- Data-FormValidator -- Reports invalid field as valid when untaint_all_constraints used Mark Stosberg (Jun 13)
- Re: CVE Request -- Data-FormValidator -- Reports invalid field as valid when untaint_all_constraints used Josh Bressers (Jun 13)