Bug 1607283 (CVE-2018-4182)

Summary:	CVE-2018-4182 cups: Sandbox bypass due to insecure error handling
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	bmcclain, dblechte, dfediuck, eedri, jpopelka, mgoldboi, michal.skrivanek, sbonazzo, sherold, twaugh, ylavi, zdohnal
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A Sandbox bypass has been discovered in cups on macOS due to insecure error handling. An attacker that has obtained sandboxed root access can use this flow to escape the sandbox.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-07-25 09:18:58 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:	1607293, 1607295
Bug Blocks:	1607292

Description Andrej Nemec 2018-07-23 08:08:50 UTC

It is possible to cause cups-exec to execute backends without a sandbox profile by causing cupsdCreateProfile() to fail.  An attacker that has obtained sandboxed root access can accomplish this by setting the CUPS temporary directory to immutable using chflags, which will prevent the profile from being written to disk.

References:

https://blog.gdssecurity.com/labs/2018/7/11/cups-local-privilege-escalation-and-sandbox-escapes.html

Upstream patch:

https://github.com/apple/cups/commit/d47f6aec436e0e9df6554436e391471097686ecc

Comment 1 Andrej Nemec 2018-07-23 08:31:41 UTC

Created cups tracking bugs for this issue:

Affects: fedora-all [bug 1607293]

Comment 3 Riccardo Schirone 2018-07-25 09:16:40 UTC

Fedora and RHEL are not affected by this flaw since Sandbox feature is not enabled on Linux.

Comment 4 Riccardo Schirone 2018-08-28 13:00:24 UTC

Statement:

This issue did not affect the versions of cups as shipped with Red Hat Enterprise Linux as cups on Linux does not support the Sandbox feature.