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                             CERT-Renater

                 Note d'Information No. 2018/VULN194
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DATE                : 22/05/2018

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running curl versions prior to 7.60.0.

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https://curl.haxx.se/docs/adv_2018-82c2.html
https://curl.haxx.se/docs/adv_2018-b138.html
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FTP shutdown response buffer overflow

Project curl Security Advisory, May 16th 2018 - Permalink


VULNERABILITY

curl might overflow a heap based memory buffer when closing down an FTP
connection with very long server command replies.

When doing FTP transfers, curl keeps a spare "closure handle" around
internally that will be used when an FTP connection gets shut down since
the original curl easy handle is then already removed.

FTP server response data that gets cached from the original transfer
might then be larger than the default buffer size (16 KB) allocated in
the "closure handle", which can lead to a buffer overwrite. The contents
and size of that overwrite is controllable by the server.

This situation was detected by an assert() in the code, but that was of
course only preventing bad stuff in debug builds. This bug is very
unlikely to trigger with non-malicious servers.

We are not aware of any exploit of this flaw.


INFO

This bug was introduced in April 2017 in this commit when we introduced
the use of increased buffer sizes for FTP.

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2018-1000300 to this issue.

CWE-122: Heap-based Buffer Overflow


AFFECTED VERSIONS

    Affected versions: curl 7.54.1 to and including curl 7.59.0
    Not affected versions: curl < 7.54.1 and curl >= 7.60.0

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


THE SOLUTION

In curl version 7.60.0, curl will return an error if this situation happens.

A patch for CVE-2018-1000300 is available.


RECOMMENDATIONS

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

A - Upgrade curl to version 7.60.0

B - Apply the patch to your version and rebuild

C - Avoing using FTP


TIME LINE

It was reported to the curl project on March 22, 2018

We contacted distros@openwall on May 7, 2018.

curl 7.60.0 was released on May 16 2018, coordinated with the
publication of this advisory.


CREDITS

Detected by Dario Weisser. Patch by Daniel Stenberg.

Thanks a lot!

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RTSP bad headers buffer over-read

Project curl Security Advisory, May 16th 2018 - Permalink


VULNERABILITY

curl can be tricked into reading data beyond the end of a heap based
buffer used to store downloaded content.

When servers send RTSP responses back to curl, the data starts out with
a set of headers. curl parses that data to separate it into a number of
headers to deal with those appropriately and to find the end of the
headers that signal the start of the "body" part.

The function that splits up the response into headers is called
Curl_http_readwrite_headers() and in situations where it can't find a
single header in the buffer, it might end up leaving a pointer pointing
into the buffer instead of to the start of the buffer which then later
on may lead to an out of buffer read when code assumes that pointer
points to a full buffer size worth of memory to use.

This could potentially lead to information leakage but most likely a
crash/denial of service for applications if a server triggers this flaw.

We are not aware of any exploit of this flaw.


INFO

This bug was originally introduced in May 2003 in this commit but it
didn't become a problem until we added RTSP in January 2010 in this commit.

We have only proven this to trigger with RTSP traffic even though this
is code shared with HTTP. We believe this is not a problem for HTTP
transfers.

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2018-1000301 to this issue.

CWE-126: Buffer Over-read


AFFECTED VERSIONS

    Affected versions: curl 7.20.0 to and including curl 7.59.0
    Not affected versions: curl < 7.20.0 and curl >= 7.60.0

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


THE SOLUTION

In curl version 7.60.0, curl makes sure to restore the pointer back to
where its supposed to point.

A patch for CVE-2018-1000301 is available.


RECOMMENDATIONS

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

A - Upgrade curl to version 7.60.0

B - Apply the patch to your version and rebuild


TIME LINE

It was reported to the curl project on March 24, 2018

We contacted distros@openwall on May 7, 2018.

curl 7.60.0 was released on May 16 2018, coordinated with the
publication of this advisory.


CREDITS

Detected by OSS-fuzz. Assisted by Max Dymond. Patch by Daniel Stenberg.

Thanks a lot!


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