Vulnerability CVE-2019-3842


Published: 2019-04-09

Description:
In systemd before v242-rc4, it was discovered that pam_systemd does not properly sanitize the environment before using the XDG_SEAT variable. It is possible for an attacker, in some particular configurations, to set a XDG_SEAT environment variable which allows for commands to be checked against polkit policies using the "allow_active" element rather than "allow_any".

See advisories in our WLB2 database:
Topic
Author
Date
Med.
systemd Seat Verification Active Session Spoofing
Jann Horn
24.04.2019

Type:

CWE-264

(Permissions, Privileges, and Access Controls)

Vendor: Debian
Product: Debian linux 
Version: 8.0;
Vendor: Redhat
Product: Enterprise linux 
Version: 7.0;
Vendor: Fedoraproject
Product: Fedora 
Version: 30;
Vendor: Systemd project
Product: Systemd 
Version: 242; 241;

CVSS2 => (AV:L/AC:M/Au:N/C:P/I:P/A:P)

CVSS Base Score
Impact Subscore
Exploitability Subscore
4.4/10
6.4/10
3.4/10
Exploit range
Attack complexity
Authentication
Local
Medium
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
Partial
Partial

 References:
http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00062.html
http://packetstormsecurity.com/files/152610/systemd-Seat-Verification-Active-Session-Spoofing.html
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3842
https://lists.debian.org/debian-lts-announce/2019/04/msg00022.html
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/STR36RJE4ZZIORMDXRERVBHMPRNRTHAC/
https://www.exploit-db.com/exploits/46743/

Related CVE
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The manager_invoke_notify_message function in systemd 231 and earlier allows local users to cause a denial of service (assertion failure and PID 1 hang) via a zero-length message received over a notify socket.
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