** Information type changed from Private Security to Public Security
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https://bugs.launchpad.net/bugs/1717490
Title:
LightDM keeps plain text login password in memory
Status in Light Display Manager:
New
Status in lightdm package in Ubuntu:
New
Bug description:
The lightdm process keeps the user password in memory, if the lightdm-
greeter is used. This seems to be the case on Ubuntu up to the recent
17.04 version. The issue was validated with lightdm 1.22.0-0ubuntu2
(17.04) and 1.10.6-0ubuntu1 (14.04)
Example:
root@victim:~# ps fauxw | grep lightdm
root 889 0.0 0.2 379344 8436 ? SLsl 12:43 0:00
/usr/sbin/lightdm
root 968 1.3 1.8 379900 72804 tty7 Ssl+ 12:43 0:01 \_
/usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm/root/:0
-nolisten tcp vt7 -novtswitch
root 1103 0.0 0.1 243564 6724 ? Sl 12:43 0:00 \_ lightdm
--session-child 12 19
root 2074 0.0 0.0 21328 976 pts/0 S+ 12:45 0:00
\_ grep --color=auto lightdm
root@victim:~# gcore 1103
[...]
Saved corefile core.1103
root@victim:~# strings core.1103 | grep -A5 -B5 secretpassword
ttyCH0
ttyCH1
#...ttyCH63
# Moxa Intellio serial
_pammodutil_getspnam_svbl_2
secretpassword
gkr_system_authtok
-UN*X-FAIL-svbl
svbl
1000:1000:svbl,,,
/home/svbl
root@victim:~#
As far as I can tell it seems that the password is not cleared form
memory after passing it to PAM. This is not a direct vulnerability or
breaking a security boundary (root access required to dump the memory)
but it seems not to be necessary for lightdm to keep the pw in memory.
A similar issue was reported to gnome-keyring-daemon, where the need
of keeping the password is a bit more understandable
(https://bugzilla.gnome.org/show_bug.cgi?id=764014).
Do you see any reason why LightDM needs to keep the password in
memory?
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