Bug 1661102 (CVE-2018-15127)

Summary:	CVE-2018-15127 libvncserver: Heap out-of-bounds write in rfbserver.c in rfbProcessFileTransferReadBuffer() allows for potential code execution
Product:	[Other] Security Response	Reporter:	Sam Fowler <sfowler>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	negativo17, ppisar, rdieter
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-10 10:44:18 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Bug Depends On:	1661104, 1661103, 1662995, 1662996, 1662997
Bug Blocks:	1661105

Description Sam Fowler 2018-12-20 06:47:22 UTC

LibVNC before commit 502821828ed00b4a2c4bef90683d0fd88ce495de contains a heap out-of-bound write vulnerability in the server code of the file transfer extension, which can result in remote code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in 502821828ed00b4a2c4bef90683d0fd88ce495de and later.


External Reference:

https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-028-libvnc-heap-out-of-bound-write/


Upstream Patch:

https://github.com/LibVNC/libvncserver/commit/502821828ed00b4a2c4bef90683d0fd88ce495de

Comment 1 Sam Fowler 2018-12-20 06:47:35 UTC

Created libvncserver tracking bugs for this issue:

Affects: epel-7 [bug 1661104]
Affects: fedora-all [bug 1661103]

Comment 2 Sam Fowler 2018-12-20 07:00:08 UTC

Upstream Issue:

https://github.com/LibVNC/libvncserver/issues/243

Comment 4 Sam Fowler 2018-12-20 08:01:53 UTC

Reference:

https://seclists.org/oss-sec/2018/q4/212

Comment 9 Petr Pisar 2019-01-10 10:03:41 UTC

Final correction was handled in <https://github.com/LibVNC/libvncserver/pull/276>.

A complete fix for this issue consists of these three upstream commits:

commit 502821828ed00b4a2c4bef90683d0fd88ce495de
Author: Christian Beier <dontmind@freeshell.org>
Date:   Sun Oct 21 20:21:30 2018 +0200

    LibVNCServer: fix heap out-of-bound write access
    
    Closes #243

commit 15bb719c03cc70f14c36a843dcb16ed69b405707
Author: Christian Beier <dontmind@freeshell.org>
Date:   Sun Jan 6 15:13:56 2019 +0100

    Error out in rfbProcessFileTransferReadBuffer if length can not be allocated
    
    re #273

commit 09e8fc02f59f16e2583b34fe1a270c238bd9ffec
Author: Petr Písař <ppisar@redhat.com>
Date:   Mon Jan 7 10:40:01 2019 +0100

    Limit lenght to INT_MAX bytes in rfbProcessFileTransferReadBuffer()
    
    This ammends 15bb719c03cc70f14c36a843dcb16ed69b405707 fix for a heap
    out-of-bound write access in rfbProcessFileTransferReadBuffer() when
    reading a transfered file content in a server. The former fix did not
    work on platforms with a 32-bit int type (expected by rfbReadExact()).
    
    CVE-2018-15127
    <https://github.com/LibVNC/libvncserver/issues/243>
    <https://github.com/LibVNC/libvncserver/issues/273>

Comment 10 errata-xmlrpc 2019-01-15 09:14:59 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2019:0059 https://access.redhat.com/errata/RHSA-2019:0059