Vulnerability CVE-2019-13272


Published: 2019-07-17

Description:
In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to create a ptrace relationship, which allows local users to obtain root access by leveraging certain scenarios with a parent-child process relationship, where a parent drops privileges and calls execve (potentially allowing control by an attacker). One contributing factor is an object lifetime issue (which can also cause a panic). Another contributing factor is incorrect marking of a ptrace relationship as privileged, which is exploitable through (for example) Polkit's pkexec helper with PTRACE_TRACEME. NOTE: SELinux deny_ptrace might be a usable workaround in some environments.

See advisories in our WLB2 database:
Topic
Author
Date
High
Linux Kernel 4.10 < 5.1.17 PTRACE_TRACEME pkexec Local Privilege Escalation
Anonymouse
26.07.2019
High
Linux Polkit pkexec Helper PTRACE_TRACEME Local Root
Brendan Coles
24.10.2019
Low
Linux PTRACE_TRACEME Local Root
nu11secur1ty
29.03.2020

Type:

CWE-264

(Permissions, Privileges, and Access Controls)

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

CVSS Base Score
Impact Subscore
Exploitability Subscore
7.2/10
10/10
3.9/10
Exploit range
Attack complexity
Authentication
Local
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Complete
Complete
Complete
Affected software
Linux -> Linux kernel 
Fedoraproject -> Fedora 
Debian -> Debian linux 

 References:
http://packetstormsecurity.com/files/153663/Linux-PTRACE_TRACEME-Broken-Permission-Object-Lifetime-Handling.html
http://packetstormsecurity.com/files/153702/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html
https://bugs.chromium.org/p/project-zero/issues/detail?id=1903
https://bugzilla.redhat.com/show_bug.cgi?id=1730895
https://bugzilla.suse.com/show_bug.cgi?id=1140671
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.1.17
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6994eefb0053799d2e07cd140df6c2ea106c41ee
https://github.com/torvalds/linux/commit/6994eefb0053799d2e07cd140df6c2ea106c41ee
https://lists.debian.org/debian-lts-announce/2019/07/msg00022.html
https://lists.debian.org/debian-lts-announce/2019/07/msg00023.html
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OGRK5LYWBJ4E4SRI4DKX367NHYSI3VOH/
https://seclists.org/bugtraq/2019/Jul/30
https://seclists.org/bugtraq/2019/Jul/33
https://www.debian.org/security/2019/dsa-4484

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