Bug 1439693 (CVE-2017-7418)

Summary:	CVE-2017-7418 proftpd: AllowChrootSymlinks control bypass
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	agk, customercare, itamar, matthias, paul, security-response-team
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	proftpd 1.3.5e, proftpd 1.3.6rc5	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-04-11 07:52:56 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:	1439695, 1439696
Bug Blocks:

Description Andrej Nemec 2017-04-06 12:09:57 UTC

ProFTPD before 1.3.5e and 1.3.6 before 1.3.6rc5 controls whether the home directory of a user could contain a symbolic link through the AllowChrootSymlinks configuration option, but checks only the last path component when enforcing AllowChrootSymlinks. Attackers with local access could bypass the AllowChrootSymlinks control by replacing a path component (other than the last one) with a symbolic link. The threat model includes an attacker who is not granted full filesystem access by a hosting provider, but can reconfigure the home directory of an FTP user.

Upstream patch (1.3.5 branch):

https://github.com/proftpd/proftpd/commit/ecff21e0d0e84f35c299ef91d7fda088e516d4ed

Upstream bug:

http://bugs.proftpd.org/show_bug.cgi?id=4295

Comment 1 Andrej Nemec 2017-04-06 12:10:31 UTC

Created proftpd tracking bugs for this issue:

Affects: epel-all [bug 1439696]
Affects: fedora-all [bug 1439695]

Comment 2 customercare 2017-04-19 13:12:54 UTC

The patch is buggy: See Bugreport #1443507

Comment 3 customercare 2017-12-14 13:38:18 UTC

FIXED and released on 2017-05-12 15:23:46 EDT 

Please close this BR.

Comment 4 Alasdair Kergon 2019-04-08 14:42:03 UTC

See bug 1697508, asking if this can be closed.