lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
From: guejez at (guejez)
Subject: SCAN Associates Advisory: perlbot 1.9.2 - Remote Command Execution

perlbot 1.9.2 - Remote Command Execution
Discovered By guejez of

 About perlbot:
 [quote from freshmeat]

 "Perlbot is an IRC bot written in Perl. It depends on Net::IRC and its
goals are
 simplicity, a small footprint, and modularity. It's meant as a more easily
 but (for now) less robust alternative to bots like eggdrop. It's also
 faster by the authors' tests. The base bot allows auto-opping, notes,
 channels, channel forwarding/bridging, etc., but much much more is possible
 the use of plugins. Many plugins are included, and it should be easy for
anyone with
 some knowledge of perl to write their own plugins"

 [/quote from freshmeat]

 perlbot is avaliable at

 Vulnerable (tested) Versions:
 Perlbot version 1.9.2 on SuSe 7.3

 Vendor Contact:
 07-22-02 - Emailed burke ^^at^^ and jmuhlich ^^at^^
            Alerted them of this vulnerability
 07-22-02 - Recieved email confirming vulnerabilties and stating fixes will
            in new version.

 -- Command Execution

 1. Due to poor input filtering and a call to the shell it is possible to
issue commands
    remotely through the irc interface of this bot.  Commands will be
executed with the
    uid at which the bot is ran.

    A more detailed explaination:

 The script tries to make a secure shell call to the aspell program by
 filtering user input. It does so in Plugins/Misc/SpelCheck/

 $text =~ s/\`//g;
 $text =~ s/\$//g;
 $text =~ s/\|//g;

 Then the call to the shell is:

 my @spell = `echo "$text"| aspell -S -a 2>&1`;

 To issue a command one could "break out" of the quotes and then issue a
 command by using ;  Inorder to prevent this more restrictive input
 needs to be put inplace.  The author said they will change from using
 to using a google API for spell checking.  This provides better support for
 people who don't have aspell installed and more security.

 2. Due to poor input filtering and a bad open() call it is possible to
execute commands.

    A more detailed explaination:

 The script tries to prevent reverse directory transversal by filtering user
 input to disallow '..' in

 $p =~ s/\.\.//g; # so people can't read arbitrary files

 $filename .= $p;

 Then in it uses this variable to open a file in an unsafe way:

 open FILE, $filename;

 This allows for command execution if $filename ends in a |.  Combin this
 with the ability to do directory transversal with .\./ and you can issue
 any command the script has permission to.

 -- Path Transveral

 1. Due to poor input filtering it is possible to read any file on the
server the
    script has permission to.

    A more detailed explaination:

 This is the same issue as above, but without appending the | to the
 filename.  This will allow an attacker to to read any file the script has
 permission to.  The file contents will be sent to the clients browser.

 Proof Of Concept:
 No proof of concept will be givin for these issues.

 According to the author a fix will be released with version 1.9.3, until
then my
 suggested patch for version 1.4.2 is to replace this line in

 $args =~ tr/\w //c;


 $args =~ s/[^\w]//g;

 For version 1.9.2 my suggested fix is to replace these lines in

 #  $text =~ tr/\w//c;

  $text =~ s/\`//g;
  $text =~ s/\$//g;
  $text =~ s/\|//g;


 $text =~ s/[^\w]//g;

 As a temperary fix, for both versions, I suggest removing the
 directory.  Since the orignal draft of this advisory there has been
multiple new
 versions of perlbot, download any above 1.9.2.

 Samy Kamkar - bugtraq post on another perlbot got me thinking.  Good shell
trick with $IFS. #vuln - various people helping with perl security issues.
 pokleyzz, sk , and all of


Powered by blists - more mailing lists