FreeBSD : ruby -- $SAFE escaping vulnerability about Exception#to_s/NameError#to_s (2a093853-2495-11e2-b0c7-000d601460a4)

Medium Nessus Plugin ID 62791


The remote FreeBSD host is missing one or more security-related updates.


The official ruby site reports :

Vulnerabilities found for Exception#to_s, NameError#to_s, and name_err_mesg_to_s() which is Ruby interpreter-internal API. A malicious user code can bypass $SAFE check by utilizing one of those security holes.

Ruby's $SAFE mechanism enables untrusted user codes to run in $SAFE >= 4 mode. This is a kind of sandboxing so some operations are restricted in that mode to protect other data outside the sandbox.

The problem found was around this mechanism. Exception#to_s, NameError#to_s, and name_err_mesg_to_s() interpreter-internal API was not correctly handling the $SAFE bits so a String object which is not tainted can destructively be marked as tainted using them. By using this an untrusted code in a sandbox can modify a formerly-untainted string destructively.

Ruby 1.8 once had a similar security issue. It fixed Exception#to_s and NameError#to_s, but name_err_mesg_to_str() issue survived previous security fix


Update the affected packages.

See Also

Plugin Details

Severity: Medium

ID: 62791

File Name: freebsd_pkg_2a093853249511e2b0c7000d601460a4.nasl

Version: $Revision: 1.4 $

Type: local

Published: 2012/11/02

Modified: 2013/06/21

Dependencies: 12634

Risk Information

Risk Factor: Medium


Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:ruby, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Patch Publication Date: 2012/11/01

Vulnerability Publication Date: 2012/08/21

Reference Information

CVE: CVE-2012-4464, CVE-2012-4466