Bug 26296 - netkit-telnetd is remotely exploitable (CVE-2020-10188)
Summary: netkit-telnetd is remotely exploitable (CVE-2020-10188)
Status: RESOLVED FIXED
Alias: None
Product: Mageia
Classification: Unclassified
Component: Security (show other bugs)
Version: 7
Hardware: All Linux
Priority: Normal critical
Target Milestone: ---
Assignee: QA Team
QA Contact: Sec team
URL:
Whiteboard: MGA7-64-OK
Keywords: advisory, validated_update
Depends on:
Blocks:
 
Reported: 2020-03-05 13:04 CET by David Walser
Modified: 2020-05-15 17:49 CEST (History)
4 users (show)

See Also:
Source RPM: netkit-telnet-0.17-19.mga8.src.rpm
CVE:
Status comment:


Attachments

Description David Walser 2020-03-05 13:04:48 CET
A blog post was published on February 28 detailing the exploit:
https://appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html

I don't see anything about a fix for the issue.

Given that we have two other telnet implementations packaged (in krb5-appl and heimdal), I don't see a purpose in retaining this insecure and unmaintained software.  It should be dropped from Cauldron.

Mageia 7 is also affected.
David Walser 2020-03-05 13:04:56 CET

Whiteboard: (none) => MGA7TOO

Comment 1 Lewis Smith 2020-03-05 19:57:48 CET
> I don't see a purpose in retaining this insecure and unmaintained software
Pretty damning. If it it easy enough to drop from Cauldron, who decides & does that? And what do we do about M7 - how do we alert users (if any)?
And to whom can this be assigned?

CC: (none) => lewyssmith

David Walser 2020-03-19 14:48:29 CET

Status comment: (none) => Package should be dropped
Assignee: bugsquad => pkg-bugs

David Walser 2020-04-07 15:54:26 CEST

See Also: (none) => https://bugs.mageia.org/show_bug.cgi?id=26451

Comment 2 David Walser 2020-04-07 15:55:29 CEST
There may be a fix for this (see Bug 26451).

Summary: netkit-telnetd is remotely exploitable => netkit-telnetd is remotely exploitable (CVE-2020-10188)

Lewis Smith 2020-04-07 20:50:18 CEST

CC: lewyssmith => (none)

Comment 3 David GEIGER 2020-04-08 10:40:19 CEST
Done for both Cauldron and mga7!

CC: (none) => geiger.david68210

Comment 4 David Walser 2020-04-08 16:55:10 CEST
Advisory:
========================

Updated netkit-telnetd packages fix security vulnerability:

A vulnerability was found where incorrect bounds checks in the telnet server’s
(telnetd) handling of short writes and urgent data, could lead to information
disclosure and corruption of heap data. An unauthenticated remote attacker
could exploit these bugs by sending specially crafted telnet packets to achieve
arbitrary code execution in the telnet server (CVE-2020-10188).

References:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10188
https://access.redhat.com/errata/RHSA-2020:1349
========================

Updated packages in core/updates_testing:
========================
netkit-telnet-0.17-18.1.mga7
netkit-telnet-server-0.17-18.1.mga7

from netkit-telnet-0.17-18.1.mga7.src.rpm

Whiteboard: MGA7TOO => (none)
Version: Cauldron => 7
Assignee: pkg-bugs => qa-bugs
Status comment: Package should be dropped => (none)

Comment 5 Herman Viaene 2020-04-10 13:35:49 CEST
MGA7-64 Plasma on Lenovo B50.
When selecting the updates in MCC I get "The following package has to be removed for others to be upgraded: krb5-appl-clients-1.0.3-10.mga7.x86_64
 (due to conflicts with netkit-telnet).
Continuing after accepting this.

CC: (none) => herman.viaene

Comment 6 Herman Viaene 2020-04-10 14:22:44 CEST
Installation completes OK.
Trying the telnet command:
$ telnet <desktop>
Trying 192.168.2.1...
telnet: connect to address 192.168.2.1: Connection timed out
Which is expected as this one has firewall active.
Running httpd this laptop and then.
$ telnet <laptop> 80
Trying 192.168.2.5...
Connected to mach5.
Escape character is '^]'.

So that one works.
But the server side has a telnetd command (unknown service after installation). Tried to run it as command, but got lost in its parrameters. Googled, but what I found is beyond me.
Comment 7 David Walser 2020-04-10 16:36:25 CEST
Interesting, looks like netkit-telnet-server doesn't ship a way to run it.  You can probably steal /etc/xinetd.d/krb5-telnet from krb5-appl-servers and use it to run /usr/sbin/telnetd from netkit-telnet-server through xinetd.
Thomas Backlund 2020-04-15 11:21:56 CEST

Keywords: (none) => advisory
CC: (none) => tmb

Comment 8 Herman Viaene 2020-05-10 10:25:47 CEST
@David
Checked, there is no such thing as /etc/xinetd.d/krb5-telnet on my system, and xinetd is untrodden territory for me right now.
I don(t fancy installing krb5-appl-servers just for the case here and nt really knwing what I am doing.
Comment 9 David Walser 2020-05-10 16:17:06 CEST
Just push it then.

Keywords: (none) => validated_update
CC: (none) => sysadmin-bugs

Herman Viaene 2020-05-11 08:47:54 CEST

Whiteboard: (none) => MGA7-64-OK

Comment 10 Mageia Robot 2020-05-15 17:49:31 CEST
An update for this issue has been pushed to the Mageia Updates repository.

https://advisories.mageia.org/MGASA-2020-0211.html

Status: NEW => RESOLVED
Resolution: (none) => FIXED


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