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Date: Thu, 18 May 2017 08:35:40 +0930
From: Simon Lees <sflees@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: terminal emulators' processing of escape sequences



On 05/02/2017 02:14 AM, Solar Designer wrote:
> Hi,
> 
> It is a well-known feature, previously discussed in here, that data
> printed to a terminal (emulator) may control that terminal, including
> making it effectively unusable until reset, and in some cases even
> pasting characters as if they were typed by the user.  Also as discussed
> what characters may be pasted varies by terminal - sometimes they can be
> arbitrary (e.g., if the terminal supports macro recording and playback
> via escape sequences) and sometimes not so (like a terminal reporting
> back its status, usually not followed by a linefeed, so not yet
> executing a shell command until further user assistance).  Here are some
> relevant threads:
> 
> http://www.openwall.com/lists/oss-security/2015/08/11/8
> http://www.openwall.com/lists/oss-security/2015/09/17/5
> http://www.openwall.com/lists/oss-security/2016/11/04/12
> 
> (I link to messages that started these threads, not necessarily to most
> informative messages in the threads.  So you might want to go through
> the threads with the "thread-next" links.)
> 
> Besides (mis)features, there may also be implementation bugs.  A couple
> of weeks ago, I brought in here vulnerabilities in terminal escape
> handling in minicom and prl-vzvncserver (both already fixed in latest
> versions by then):
> 
> http://www.openwall.com/lists/oss-security/2017/04/18/5
> 
> I already knew this wouldn't be the end of the story as some other
> terminal emulators exhibited suspicious behavior when targeted with
> streams of unusual escape sequences involving large or negative integer
> parameters.  I sent the following to the distros list on April 17,
> presented here with updates reflecting the current status.
> 
> 
> terminology:
> 
> ---
> ERR<10676>:termpty termptyesc.c:1115 _handle_esc_csi() unhandled CSI 'x': 2147483647;0x
> ERR<10676>:termpty termptyesc.c:1115 _handle_esc_csi() unhandled CSI 'x': 2147483647;0x
> ERR<10676>:termpty termptyesc.c:1115 _handle_esc_csi() unhandled CSI 'x': 2147483647;0x
> ---
> 

For reference terminology was fixed with this commit
https://phab.enlightenment.org/rTRM63d65ed4bb06094e6a8b6cafdc7c4cbfc62dd677

Thanks

-- 

Simon Lees (Simotek)                            http://simotek.net

Emergency Update Team                           keybase.io/simotek
SUSE Linux                           Adelaide Australia, UTC+10:30
GPG Fingerprint: 5B87 DB9D 88DC F606 E489 CEC5 0922 C246 02F0 014B



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