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Message-Id: <201201091605.q09G5ER0024229@red.freebsd.org>
Date: Mon, 9 Jan 2012 16:05:14 GMT
From: Denis Seleznev <denis5594@gmail.com>
To: freebsd-gnats-submit@FreeBSD.org
Subject: telnetd stack overflow exploit
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>Number:         163958
>Category:       bin
>Synopsis:       telnetd stack overflow exploit
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    gjb
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jan 09 16:10:07 UTC 2012
>Closed-Date:    Mon Jan 09 16:18:14 UTC 2012
>Last-Modified:  Mon Jan 09 16:18:14 UTC 2012
>Originator:     Denis Seleznev
>Release:        8.2-STABLE
>Organization:
>Environment:
FreeBSD elf.dyndns.org 8.2-STABLE FreeBSD 8.2-STABLE #1: Sun Sep 25 13:32:50 SAMST 2011     denis@elf.dyndns.org:/usr/obj/usr/src/sys/EEE700  i386
>Description:
Recently, i have found malicious activity on one of my machines - it was strange process "barbut.bsd" running as root and "talkng" process eating all the cpu and bandwitdh. Searching through logs, i've found strange behaviour of telnetd right before that activity:
Jan  7 17:20:06 elf kernel: pid 25119 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:07 elf kernel: pid 25120 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:08 elf kernel: pid 25121 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:08 elf kernel: pid 25122 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:09 elf kernel: pid 25123 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:10 elf kernel: pid 25124 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:11 elf kernel: pid 25125 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:11 elf kernel: pid 25126 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:13 elf kernel: pid 25129 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:14 elf kernel: pid 25130 (telnetd), uid 0: exited on signal 10 (core dumped)
Jan  7 17:20:15 elf kernel: pid 25131 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 17:20:15 elf kernel: pid 25132 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:44:51 elf kernel: pid 25281 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:45:22 elf kernel: pid 25284 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:45:53 elf kernel: pid 25285 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:46:24 elf kernel: pid 25286 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:46:55 elf kernel: pid 25287 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:47:26 elf kernel: pid 25288 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:47:57 elf kernel: pid 25289 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:48:28 elf kernel: pid 25290 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:49:04 elf kernel: pid 25293 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:49:35 elf kernel: pid 25299 (telnetd), uid 0: exited on signal 10 (core dumped)
Jan  7 18:50:06 elf kernel: pid 25302 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:50:37 elf kernel: pid 25303 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:57:26 elf kernel: pid 25319 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:57:57 elf kernel: pid 25320 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:58:28 elf kernel: pid 25321 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:58:59 elf kernel: pid 25322 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 18:59:29 elf kernel: pid 25323 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:00:00 elf kernel: pid 25324 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:00:31 elf kernel: pid 25343 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:01:02 elf kernel: pid 25346 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:01:38 elf kernel: pid 25351 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:02:09 elf kernel: pid 25361 (telnetd), uid 0: exited on signal 10 (core dumped)
Jan  7 19:02:40 elf kernel: pid 25362 (telnetd), uid 0: exited on signal 11 (core dumped)
Jan  7 19:03:11 elf kernel: pid 25363 (telnetd), uid 0: exited on signal 11 (core dumped)

It is the only such an occurence, it never happened before or after. Now i have entirely disabled inetd to prevent further attacks. I am pretty sure that infection was caused by telnetd because i have enabled only ssh and inetd+telnetd, moreover, i searched through the logs very carefully, and there was no succsessfull connections by ssh, nor telnet.
telnetd core dump: http://ifile.it/w49d81n
I have saved "talkng" file and can provide it for further investigation, if you so choose.
>How-To-Repeat:
Who knows, maybe enabling telnel, or running that "talkng" executable will reproduce the problem.
>Fix:
Disable inted, telnetd, mount /tmp with noexec, check home,/root,/tmp directory for strange executables

>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: gjb 
State-Changed-When: Mon Jan 9 16:16:40 UTC 2012 
State-Changed-Why:  
Hi, 

This is not a www category problem. 

Please see the following announcement: 

http://security.freebsd.org/advisories/FreeBSD-SA-11:08.telnetd.asc 

Glen 



Responsible-Changed-From-To: freebsd-www->gjb 
Responsible-Changed-By: gjb 
Responsible-Changed-When: Mon Jan 9 16:16:40 UTC 2012 
Responsible-Changed-Why:  
I closed it. 


http://www.freebsd.org/cgi/query-pr.cgi?pr=163958 
>Unformatted:
