====================================================================

                             CERT-Renater

                 Note d'Information No. 2020/VULN003
_____________________________________________________________________

DATE                : 14/01/2020

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running libcurl versions prior to 7.68.0.

=====================================================================
https://curl.haxx.se/docs/CVE-2019-15601.html
_____________________________________________________________________

SMB access smuggling via FILE URL on Windows
============================================

Project curl Security Advisory, January 8th 2020 -
[Permalink](https://curl.haxx.se/docs/CVE-2019-15601.html)

VULNERABILITY
-------------

libcurl can be told to load a file from a `FILE://` URL. It will then
load the file from the path specified in the URL from the local file system.

If you craft the given path so that it starts with two slashes (or
backslashes) followed by a host name, Windows systems will automatically
treat that as a request to access the host name using SMB instead of
reading a local file with that name. This is not expected nor documented
libcurl behavior.

Applications allowing users to provide URLs or parts of URLs could be
vulnerable to this flaw. Both the curl tool and library.

Example URL exploiting this: `file://localhost//hostname/home/secret.txt`.

We are not aware of any exploit of this flaw.

INFO
----

This bug only exists when libcurl runs on a Microsoft Windows operating
system.

This bug exists in the first code import we have, from 1999.

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2019-15601 to this issue.

CWE-20: Improper Input Validation

Severity: 3.0 (Low)

AFFECTED VERSIONS
-----------------

- Affected versions: all versions to and including 7.67.0
- Not affected versions: libcurl >= 7.68.0

libcurl is used by many applications, but not always advertised as such.

THE SOLUTION
------------

A [fix for
CVE-2019-15601](https://github.com/curl/curl/commit/1b71bc532bde8621fd3260843f8197182a467ff2)

RECOMMENDATIONS
--------------

We suggest you take one of the following actions immediately, in order
of preference:

 A - Upgrade curl to version 7.68.0

 B - Apply the patch to your version and rebuild

 C - do not use `FILE://` URLs

TIMELINE
--------

The issue was reported to the curl project on October 31, 2019. The
initial fix was done, verified and communicated with the reporter on
November 7, 2019.

This advisory was posted on January 8th 2020.

CREDITS
-------

Reported by Fernando Muñoz. Patch by Daniel Stenberg.

Thanks a lot!



 / daniel.haxx.se | Get the best commercial curl support there is - from
                    me
                  | Private help, bug fixes, support, ports, new
                    features
                  | https://www.wolfssl.com/contact/

=========================================================
+ CERT-RENATER        | tel : 01-53-94-20-44            +
+ 23/25 Rue Daviel    | fax : 01-53-94-20-41            +
+ 75013 Paris         | email:cert@support.renater.fr   +
=========================================================