Bug 1766700 (CVE-2019-17042)

Summary:	CVE-2019-17042 rsyslog: heap-based overflow in contrib/pmcisconames/pmcisconames.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:	dapospis, ebenes, jlieskov, jvymazal, lkundrak, mah.darade, rsroka, tosykora, yozone
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:	2020-03-31 22:35:42 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:	1766701, 1768323, 1768324
Bug Blocks:	1766703

Description Guilherme de Almeida Suckevicz 2019-10-29 17:09:28 UTC

An issue was discovered in Rsyslog v8.1908.0. contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for Cisco log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon), but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The message will then be considered valid, and the parser will eat up the nonexistent colon delimiter. In doing so, it will decrement lenMsg, a signed integer, whose value was zero and now becomes minus one. The following step in the parser is to shift left the contents of the message. To do this, it will call memmove with the right pointers to the target and destination strings, but the lenMsg will now be interpreted as a huge value, causing a heap overflow.

Reference:
https://github.com/rsyslog/rsyslog/pull/3883

Comment 1 Guilherme de Almeida Suckevicz 2019-10-29 17:09:45 UTC

Created rsyslog tracking bugs for this issue:

Affects: fedora-all [bug 1766701]

Comment 2 Huzaifa S. Sidhpurwala 2019-11-04 05:13:41 UTC

Upstream commit: https://github.com/rsyslog/rsyslog/pull/3883/commits/abc0960a7561e18944a0e08d48f4eb570ea7435a

A flaw in the way rsyslog parses Cisco log messages. Crafted messages could result in crash or even code execution, however since log messages are normally generated by the system and privs are required to generate specially-crafted messages, it is more likely to result in rsyslog crash rather than code execution.

Comment 4 errata-xmlrpc 2020-03-31 19:09:32 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:1000 https://access.redhat.com/errata/RHSA-2020:1000

Comment 5 Product Security DevOps Team 2020-03-31 22:35:42 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2019-17042

Comment 6 errata-xmlrpc 2020-04-28 15:42:16 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:1702 https://access.redhat.com/errata/RHSA-2020:1702