Date: Fri, 3 Oct 2014 15:26:09 +0400 From: Solar Designer <solar@...nwall.com> To: oss-security@...ts.openwall.com Cc: rgerhards@...adiscon.com, joey@...odrom.org Subject: Re: sysklogd vulnerability (CVE-2014-3634) On Fri, Oct 03, 2014 at 11:24:43AM +0000, mancha wrote: > On Fri, Oct 03, 2014 at 09:12:28AM +0000, mancha wrote: > > In sysklogd's syslogd, invalid priority values between 192 and 1023 > > (directly or arrived at via overflow wraparound) can propagate through > > code causing out-of-bounds access to the f_pmask array within the > > 'filed' structure by up to 104 bytes past its end. Though most likely > > insufficient to reach unallocated memory because there are around 544 > > bytes past f_pmask in 'filed' (mod packing and other differences), > > incorrect access of fields at higher positions of the 'filed' > > structure definition can cause unexpected behavior including message > > mis-classification, forwarding issues, message loss, or other. > > To expand on the above, because the out-of-bounds access is limited to > the filed structure, the effect on message handling, etc. appears > limited to the would-be attacker's own message. Unlike the more serious > impact seen in rsyslog, my limited testing and code review suggests the > flaw, while there, has no real security impact. Nevertheless, my patch > fixes the handling of malformed PRI parts. What about the DoS impact claimed here, though? - http://www.rsyslog.com/remote-syslog-pri-vulnerability-cve-2014-3683/ sysklogd ~~~~~~~~ A segfault seems possible in sysklogd if a negative facility value (due to integer overrun in facility parsing) is used. This could be used to carry out a remote DoS. If this can be used to crash syslogd, it's "real security impact", even if rather limited. Have you tried triggering this condition (getting syslogd to crash)? Alexander
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