Decompiling Java Bytecode (PicoCTF 2022 #34 'fresh-java')

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  • เผยแพร่เมื่อ 28 ส.ค. 2024

ความคิดเห็น • 16

  • @rajan_0
    @rajan_0 2 ปีที่แล้ว +9

    3:39 the question I ask my self everyday.

  • @thecrownofnoah9100
    @thecrownofnoah9100 2 ปีที่แล้ว +3

    Do more picoCTF I like watching these videos

  • @bladesvlogs4965
    @bladesvlogs4965 2 ปีที่แล้ว

    Another good one 👍

  • @wolfrevokcats7890
    @wolfrevokcats7890 2 ปีที่แล้ว +4

    7:35 cat flag.txt | tr -d '
    '
    Thanks John, always learn a new trick from you

  • @tonyitalia7798
    @tonyitalia7798 2 ปีที่แล้ว +1

    00:51 Interesting. At the beginning of the code there is CAFE.
    In Brazil (café) CAFE = coffee in the USA.

    • @DaniSpeh
      @DaniSpeh 2 ปีที่แล้ว +11

      For more info, CAFE BABE is a magic number for .class. It's intentional and was created by the developers. CAFE because some people call coffee java. BABE because they liked it. There was also CAFE DEAD for objects and that's because during the development they used to hang out in a Grateful Dead cafe. Anyways those magic numbers are very common and if you open different files with a hex editor you will see a lot of them have printable ASCII characters somewhere at the beginning. For example gif has "GIF89a" or ""GIF87a", executable elf files (linux) have "ELF" , png have "PNG". In itsec you will sometimes need those magic numbers to hack webapps. For example in fileuploads that allow only pictures to hide code to create a backdoor. Also the "file" command John is using in practically every video so far, uses, among other things, magic numbers to identify what file it is. For more info you can look up "Magic numbers" and about the CAFE BABE story "Gosling CAFE BABE"

    • @Redstoneprojrjr
      @Redstoneprojrjr 2 ปีที่แล้ว

      This comment is so skull emoji

  • @mrmonday2000
    @mrmonday2000 2 ปีที่แล้ว +1

    Honestly just use the JD eclipse plugin

  • @nekokasha_mizusu
    @nekokasha_mizusu 2 ปีที่แล้ว +3

    it seems that jadx does not accept .class files, only .jar file. I don't know why but help page mentioned that.

    • @inazumaeleven9102
      @inazumaeleven9102 2 ปีที่แล้ว +1

      It worked on my machine with the .class

    • @ShootingUtah
      @ShootingUtah 2 ปีที่แล้ว

      It claims to take .class files in the list of accepted files?!???

    • @lovelycode7173
      @lovelycode7173 2 ปีที่แล้ว +2

      It does accept class files, but if you read the stack trace of jadx it says it's an unsupported class version which means he's trying to decompile a file with a greater major version than the JDK installed on his computer. Java is backwards compatible, not forwards.

  • @ahmedmani1051
    @ahmedmani1051 2 ปีที่แล้ว +1

    use jadx-gui instead its way easier to work with

  • @mhamademad
    @mhamademad ปีที่แล้ว

    what if they were not ordered, your little extraction would've been useless, but nevertheless cool video to look at.

  • @sandra8139
    @sandra8139 ปีที่แล้ว

    I am giving malware by telling you about lookout security app and asking you to remove it please

  • @LepriKon17
    @LepriKon17 2 ปีที่แล้ว

    I did with ghidra ^.^ this is bad ye? hh