Bug 1768463 (CVE-2019-17455)

Summary:	CVE-2019-17455 libntlm: stack-based buffer overflow in buildSmbNtlmAuthRequest in smbutil.c
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bkearney, gdeschner, kevin, moceap, tlestach
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libntlm 1.6	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the libntlm NTLM library where it was vulnerable to a buffer overflow in the buildSmbNtlmAuthRequest_userlen() function. If an application using this library does not check input length before calling the function, an attacker could use this flaw to send a specially crafted request that could crash the application, or possibly trigger code execution.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-25 09:54:12 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1768464, 1768465, 1771558, 1771559, 1771560
Bug Blocks:	1768466

Description Guilherme de Almeida Suckevicz 2019-11-04 14:06:43 UTC

Libntlm through 1.5 relies on a fixed buffer size for tSmbNtlmAuthRequest, tSmbNtlmAuthChallenge, and tSmbNtlmAuthResponse read and write operations, as demonstrated by a stack-based buffer over-read in buildSmbNtlmAuthRequest in smbutil.c for a crafted NTLM request.

Reference:
https://gitlab.com/jas/libntlm/issues/2

Comment 1 Guilherme de Almeida Suckevicz 2019-11-04 14:07:04 UTC

Created libntlm tracking bugs for this issue:

Affects: epel-7 [bug 1768465]
Affects: fedora-all [bug 1768464]

Comment 4 Cedric Buissart 2020-02-05 17:24:47 UTC

Mitigation:

The calling application must verify that the input  username and domain fit in the 1024 byte buffer.

Comment 5 Cedric Buissart 2020-03-19 11:29:31 UTC

Statement:

The vulnerability is rated Medium because no package in Red Hat Enterprise Linux versions 6 and 7 is using Libntlm. Most 3rd party applications using Libntlm are command line clients and would be affected via a command line option or a configuration file, which are local vectors.

Comment 6 Cedric Buissart 2020-04-21 12:33:36 UTC

Upstream fix :
https://gitlab.com/jas/libntlm/-/commit/b967886873fcf19f816b9c0868465f2d9e5df85e

Regression test:
https://gitlab.com/jas/libntlm/-/commit/aa975994cf9cf39c33ce33a1b2988277c456dec1