memgrdpeek

memgrdpeek

Intention

memgrdpeek tries to evaluate the effective protection of the golang library memguard.

The go app uses a memguard.LockedBuffer to protect its data. A python script tries to extract protected memory areas from the running go app. This script reads all used memory areas from /proc/app-pid/maps and tries to find 32 byte long areas within /proc/app-pid/mem.

How to use

Tested on Linux only! Might work on OS X, but not on Windows.

Get this project:

go get github.com/denisbrodbeck/memgrdpeek
cd "$GOPATH/src/github.com/denisbrodbeck/memgrdpeek"

• [build using make]
• run memgrdpeek
• open another terminal
• run sudo memory_reader.py

What it does

Essentially we try to create a data structures with a memory protected area within it:

type message struct {
  ID        []byte                 // 32 byte
  Recipient []byte                 // 32 byte
  Sender    []byte                 // 32 byte
  Message   *memguard.LockedBuffer // Gets 32 byte input
  Meta      []byte                 // 32 byte
}

Create a new message:

msg := newMessage(
  []byte("(((id    | 1234567890123456  )))"),
  []byte("(((recip | bobby@spacer.com  )))"),
  []byte("(((sender| eva@secretmoon.m  )))"),
  []byte("(((msg   | VERY SECRET VERY  )))"), // this should be protected
  []byte("(((meta  | 2017-10-21 10:26  )))"),
  )

After reading the process's memory, one expects to discover, that all buffers are visible except the Message buffer.

Output

Starting memguarded app:

$ bin/memgrdpeek

Running under PID: 25921
Press enter after running 'memory_reader.py' to exit...

And run memory_reader.py with the provided pid:

$ sudo ./memory_reader.py --pid 25921

INFO:root:Trying pid 25921
INFO:root:Scanning pid 25921 range 7ffec4585000-7ffec45a6000 [stack];
INFO:root:Found 0 candidate pointers
INFO:root:Scanning pid 25921 range 7f038c647000-7f038c6e7000 ;
INFO:root:Found 0 candidate pointers
INFO:root:Scanning pid 25921 range c41fff8000-c420100000 ;
INFO:root:Found 7 candidate pointers
842350543008:    QT_QPA_PLATFORMTHEME=appmenu-qt5LC_TIME=de_DE.UTF-8SHELL=/usr/bin/zshLC_NUMERIC=de_DE.UTF-8LC_PAPER=de_DE.UTF-8
842350543296:    XAUTHORITY=/home/dev/.XauthorityXDG_SESSION_DESKTOP=ubuntuGDMSESSION=ubuntuUPSTART_EVENTS=xsession startedLC_MEASUREMENT=de_DE.UTF-8
842350544192:    (((id    | 1234567890123456  )))(((recip | bobby@spacer.com  )))(((sender| eva@secretmoon.m  )))(((meta  | 2017-10-21 10:26  )))
842350544224:    (((recip | bobby@spacer.com  )))(((sender| eva@secretmoon.m  )))(((meta  | 2017-10-21 10:26  )))
842350544256:    (((sender| eva@secretmoon.m  )))(((meta  | 2017-10-21 10:26  )))
842350544288:    (((meta  | 2017-10-21 10:26  )))
842350730936:    ` �� ��E
 �`E
 �@E
 ���KPCO��K� ���KpCO` ���J�_d� ��K
INFO:root:Scanning pid 25921 range c000000000-c000001000 ;
INFO:root:Found 0 candidate pointers
INFO:root:Scanning pid 25921 range 56a000-58c000 ;
INFO:root:Found 0 candidate pointers

Studding the output one can see, that the message fields are clearly visible from memory. Ouput only skips the memory areas of the Message field.

(((id | 1234567890123456 )))(((recip | bobby@spacer.com )))(((sender| eva@secretmoon.m )))(((meta | 2017-10-21 10:26 )))

Conclusion

Using the described approach I wasn't able to extract the content of the protected buffer.

An experienced low-level/assembly hacker would probably be able to extract more meaningful content. PR's are welcome :)

Credits

The python extraction code wouldn't be possible without prior work of Vayu. Vayu's project extracts the unencrypted private key from hashicorps vault.

License

The MIT License (MIT) — Denis Brodbeck. Please have a look at the LICENSE for more details.