Subject: [ASA-201902-11] lib32-libcurl-gnutls: arbitrary code execution

Arch Linux Security Advisory ASA-201902-11
==========================================

Severity: High
Date    : 2019-02-12
CVE-ID  : CVE-2018-16890 CVE-2019-3822 CVE-2019-3823
Package : lib32-libcurl-gnutls
Type    : arbitrary code execution
Remote  : Yes
Link    : https://security.archlinux.org/AVG-876

Summary
=======

The package lib32-libcurl-gnutls before version 7.64.0-1 is vulnerable
to arbitrary code execution.

Resolution
==========

Upgrade to 7.64.0-1.

# pacman -Syu "lib32-libcurl-gnutls>=7.64.0-1"

The problems have been fixed upstream in version 7.64.0.

Workaround
==========

None.

Description
===========

- CVE-2018-16890 (arbitrary code execution)

libcurl versions from 7.36.0 to before 7.64.0 is vulnerable to a heap
buffer out-of-bounds read. The function handling incoming NTLM type-2
messages (`lib/vauth/ntlm.c:ntlm_decode_type2_target`) does not
validate incoming data correctly and is subject to an integer overflow
vulnerability. Using that overflow, a malicious or broken NTLM server
could trick libcurl to accept a bad length + offset combination that
would lead to a buffer read out-of-bounds.

- CVE-2019-3822 (arbitrary code execution)

libcurl versions from 7.36.0 to before 7.64.0 are vulnerable to a
stack-based buffer overflow. The function creating an outgoing NTLM
type-3 header
(`lib/vauth/ntlm.c:Curl_auth_create_ntlm_type3_message()`), generates
the request HTTP header contents based on previously received data. The
check that exists to prevent the local buffer from getting overflowed
is implemented wrongly (using unsigned math) and as such it does not
prevent the overflow from happening. This output data can grow larger
than the local buffer if very large "nt response" data is extracted
from a previous NTLMv2 header provided by the malicious or broken HTTP
server. Such a "large value" needs to be around 1000 bytes or more. The
actual payload data copied to the target buffer comes from the NTLMv2
type-2 response header.

- CVE-2019-3823 (arbitrary code execution)

libcurl versions from 7.34.0 to before 7.64.0 are vulnerable to a heap
out-of-bounds read in the code handling the end-of-response for SMTP.
If the buffer passed to `smtp_endofresp()` isn't NUL terminated and
contains no character ending the parsed number, and `len` is set to 5,
then the `strtol()` call reads beyond the allocated buffer. The read
contents will not be returned to the caller.

Impact
======

A malicious remote server could execute arbitrary code by sending
malicious NTLM or SMTP replies.

References
==========

https://curl.haxx.se/docs/CVE-2018-16890.html
https://github.com/curl/curl/commit/b780b30d1377adb10bbe774835f49e9b237fb9bb
https://curl.haxx.se/docs/CVE-2019-3822.html
https://github.com/curl/curl/commit/50c9484278c63b958655a717844f0721263939cc
https://curl.haxx.se/docs/CVE-2019-3823.html
https://github.com/curl/curl/commit/39df4073e5413fcdbb5a38da0c1ce6f1c0ceb484
https://security.archlinux.org/CVE-2018-16890
https://security.archlinux.org/CVE-2019-3822
https://security.archlinux.org/CVE-2019-3823