Date: Wed, 26 Nov 2014 00:18:13 +0100 From: Ángel González <angel@...its.net> To: oss-security@...ts.openwall.com Cc: mmcallis@...hat.com, cve-assign@...re.org, 767227@...s.debian.org, sven.schwedas@....at, axkibe@...il.com Subject: Re: Re: CVE request: lsyncd command injection On 20-11-2014 Mitre wrote: > > There is a command injection flaw in lsyncd, a file change monitoring > > and synchronization daemon: > > > > https://github.com/axkibe/lsyncd/issues/220 > > > > https://github.com/creshal/lsyncd/commit/18f02ad013b41a72753912155ae2ba72f2a53e52 > > > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=767227 > > Use CVE-2014-8990. The scope of this CVE ID includes both: > > 1. code execution with ` characters or other characters that are > special to a shell > 2. denial of service scenarios in which a user with write access > to a local directory uses special characters to make > synchronization fail (might have security relevance in some > scenarios) > > The MITRE CVE team does not have a Lua expert. The code change adds: > > local path1 = event.path:gsub ('"', '\\"'):gsub ('`', '\\`'):gsub ('%$','\\%$') > local path2 = event2.path:gsub ('"', '\\"'):gsub ('`', '\\`'):gsub ('%$','\\%$') > > This does not seem to be the typical fix approach for unsafe input to > a shell. Has anyone concluded that this is an incomplete fix that ought > to be modified before the 2.1.6 release? It is indeed an incomplete fix: * The gsub ('%$','\\%$') works in lua5.1, but under lua5.2 the second % character makes lsyncd fail with the error "stdin:1: invalid use of '%' in replacement string". Thus allowing a complete denial of service * Not all metacharacters are filtered, so command execution is still present. In particular, the escaped characters can be prefixed with a backslash to bypass the filter. The attached patch should hopefully solve these issues. View attachment "0001-Properly-sanitize-mv-parameters-CVE-2014-8990.patch" of type "text/x-patch" (1694 bytes)
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.