Date: Mon, 27 Jun 2011 11:21:36 +0800 From: Eugene Teo <eugeneteo@...nel.org> To: oss-security@...ts.openwall.com CC: Vasiliy Kulikov <segoon@...nwall.com> Subject: Re: CVE request: kernel: taskstats/procfs io infoleak On 06/24/2011 08:34 PM, Vasiliy Kulikov wrote: > Hi, > > On Tue, Jun 21, 2011 at 15:24 -0400, Josh Bressers wrote: >>> /* >>> * This program tries to learn whether ~user/.ssh/authorized_keys exists >>> * and is nonempty for any user on local machine. It uses world-readable >>> * taskstats' nature to get somewhat private io statistics information. If >>> * implant taskstats or /proc//io polling into ssh client, it would be >>> * possible to learn precise authorized_keys' size (and estimate private >>> * key's(s') size). >> >> Are you considering this a flaw, or just an interesting security exercise? >> Nothing currently comes to mind, but it's possible there could be other >> data where knowing it exists and the size would be useful. > > It can be used to learn ssh and ftp password length. If privsep is > enabled in openssh and vsftpd, the unprivileged process' activity very > precisely shows password information. > > For vsftpd read characters count is strlen("USER username\r\n") + > strlen("PASSWD pass\r\n") + 1, where 1 is one byte read from a pipe > related to a privileged parent. If measure statistics between user and > passwords commands, actual password length and username length can be > gathered. > > For ssh, vice versa, networking activity is constant in packets length, > but interprocess communications, specifically passwords, depend on > user input. > > For ssh pass_len = wchars - CONST, for vsftpd pass_len = rchars - CONST. > > Another daemons with more or less constant io activity might be > vulnerable too. PAM greatly complicates precise measurements. > > > I think it needs 2 CVE, one for /proc/PID/io and another for taskstats. > > https://lkml.org/lkml/2011/6/24/88 procfs io - CVE-2011-2495 taskstats - CVE-2011-2494 Thanks, Eugene
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