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Symbolic Needs 2

Symbolic Needs 2

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November 28, 2022
2 min read
symbolic-needs-2

Symbolic Needs 2

Author
Battlemonger
Category
Forensics
Points
482
Solves
18
Files
memdump
Flag
SEKAI{0x81c458e9fae445de18385a3379513acc8e191e4c2667c85aa0a52a32ec4e6d55}

Recover the private key of the wallet address 0xACa5872e497F0Cc626d1E9bA28bAEC149315266e.
Submit the key wrapped with SEKAI{}.

Let’s follow up from the last proglem with the linux.psaux plugin, to gather and display all processes:

Terminal window
$ python3 vol.py -f dump.mem linux.psaux
Volatility 3 Framework 2.3.1
Progress:  100.00        Stacking attempts finished
PID PPID    COMM    ARGS
...
1731    985 gsd-xsettings    /usr/libexec/gsd-xsettings
1787    985 ibus-x11    /usr/libexec/ibus-x11
1845    985 gnome-terminal- /usr/libexec/gnome-terminal-server
1863    1845    bash    bash
1878    1863    ncat    ncat -lvnp 1234 -c echo 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= | base32 -d > file.pyc
1886    1147    update-notifier update-notifier
1911    1863    sudo    sudo insmod LiME/src/lime-5.15.0-43-generic.ko path=dump.mem format=lime
1918    1911    sudo    sudo insmod LiME/src/lime-5.15.0-43-generic.ko path=dump.mem format=lime
...

It looks like the scammer was serving some base32 through Netcat. We also notice that it’s piped into a .pyc file, which is Python bytecode.

Run the command echo [PUT YOUR BASE32 HERE] | base32 -d > file.pyc to convert this base32 into a binary. Let’s run the .pyc with Python3:

Terminal window
$ python3 file.pyc
Usage: ./wallet password

Passing a random argument results in a FileNotFoundError:

Terminal window
$ python3 file.pyc password
Traceback (most recent call last):
  File "test2.py", line 12, in <module>
FileNotFoundError: [Errno 2] No such file or directory: 'bip39list.txt'

We can find this wordlist in the bitcoin/bips repository. If you run the binary again with the same argument it just outputs “Wrong.” We’ll need to disassemble this.

Disassemble the bytecode with the dis module:

disassembled.py
import dis
import marshal


with open('file.pyc', 'rb') as f:
    f.seek(16)
    print(dis.dis(marshal.load(f)))
Terminal window
$ python3 disassembled.py
  1           0 LOAD_CONST               0 (0)
              2 LOAD_CONST               1 (None)
              4 IMPORT_NAME              0 (sys)
              6 STORE_NAME               0 (sys)


  3           8 SETUP_FINALLY            7 (to 24)


  4          10 LOAD_NAME                0 (sys)
             12 LOAD_ATTR                1 (argv)
             14 LOAD_CONST               2 (1)
             16 BINARY_SUBSCR
             18 STORE_NAME               2 (password)
             20 POP_BLOCK
             22 JUMP_FORWARD            11 (to 46)


  5     >>   24 POP_TOP
             26 POP_TOP
             28 POP_TOP


  6          30 LOAD_NAME                3 (print)
             32 LOAD_CONST               3 ('Usage: ./wallet password')
             34 CALL_FUNCTION            1
             36 POP_TOP


  7          38 LOAD_NAME                4 (exit)
             40 CALL_FUNCTION            0
             42 POP_TOP
             44 POP_EXCEPT


 10     >>   46 BUILD_LIST               0
             48 STORE_NAME               5 (words)


 12          50 LOAD_NAME                6 (open)
             52 LOAD_CONST               4 ('bip39list.txt')
             54 LOAD_CONST               5 ('r')
             56 CALL_FUNCTION            2
             58 SETUP_WITH              14 (to 88)
             60 STORE_NAME               7 (f)


 13          62 LOAD_NAME                7 (f)
             64 LOAD_METHOD              8 (read)
             66 CALL_METHOD              0
             68 LOAD_METHOD              9 (splitlines)
             70 CALL_METHOD              0
             72 STORE_NAME               5 (words)
             74 POP_BLOCK


 12          76 LOAD_CONST               1 (None)
             78 DUP_TOP
             80 DUP_TOP
             82 CALL_FUNCTION            3
             84 POP_TOP
             86 JUMP_FORWARD             8 (to 104)
        >>   88 WITH_EXCEPT_START
             90 POP_JUMP_IF_TRUE        47 (to 94)
             92 RERAISE                  1
        >>   94 POP_TOP
             96 POP_TOP
             98 POP_TOP
            100 POP_EXCEPT
            102 POP_TOP


 15     >>  104 LOAD_CONST               6 (75673125099835840306362297188218306412669859836254678874904603942583570317024638985472)
            106 STORE_NAME              10 (code)


 18         108 LOAD_NAME               11 (bin)
            110 LOAD_NAME               10 (code)
            112 CALL_FUNCTION            1
            114 LOAD_CONST               7 (2)
            116 LOAD_CONST               1 (None)
            118 BUILD_SLICE              2
            120 BINARY_SUBSCR
            122 STORE_NAME              10 (code)


 19         124 LOAD_NAME               12 (str)
            126 LOAD_NAME               10 (code)
            128 LOAD_METHOD             13 (zfill)
            130 LOAD_NAME               14 (len)
            132 LOAD_NAME               10 (code)
            134 CALL_FUNCTION            1
            136 LOAD_CONST               8 (12)
            138 LOAD_NAME               14 (len)
            140 LOAD_NAME               10 (code)
            142 CALL_FUNCTION            1
            144 LOAD_CONST               8 (12)
            146 BINARY_MODULO
            148 BINARY_SUBTRACT
            150 BINARY_ADD
            152 CALL_METHOD              1
            154 CALL_FUNCTION            1
            156 STORE_NAME              10 (code)


 22         158 BUILD_LIST               0
            160 STORE_NAME              15 (mnemonic)


 24         162 LOAD_NAME               16 (range)
            164 LOAD_CONST               0 (0)
            166 LOAD_NAME               14 (len)
            168 LOAD_NAME               10 (code)
            170 CALL_FUNCTION            1
            172 LOAD_CONST               8 (12)
            174 CALL_FUNCTION            3
            176 GET_ITER
        >>  178 FOR_ITER                20 (to 220)
            180 STORE_NAME              17 (i)


 25         182 LOAD_NAME               15 (mnemonic)
            184 LOAD_METHOD             18 (append)
            186 LOAD_NAME                5 (words)
            188 LOAD_NAME               19 (int)
            190 LOAD_NAME               10 (code)
            192 LOAD_NAME               17 (i)
            194 LOAD_NAME               17 (i)
            196 LOAD_CONST               8 (12)
            198 BINARY_ADD
            200 BUILD_SLICE              2
            202 BINARY_SUBSCR
            204 LOAD_CONST               7 (2)
            206 CALL_FUNCTION            2
            208 LOAD_CONST               2 (1)
            210 BINARY_SUBTRACT
            212 BINARY_SUBSCR
            214 CALL_METHOD              1
            216 POP_TOP
            218 JUMP_ABSOLUTE           89 (to 178)


 27     >>  220 LOAD_NAME                3 (print)
            222 LOAD_CONST               9 ('Wrong')
            224 CALL_FUNCTION            1
            226 POP_TOP
            228 LOAD_CONST               1 (None)
            230 RETURN_VALUE
None

Let’s analyze this:

  1. The program loads the bip39 wordlist. It’s a standard wordlist used to secure crypto wallets with a mnemonic.
  2. It then stores a hardcoded integer in the variable code, converts to binary and zfills it so that length is multiple of 12.
  3. Next, it converts each 12 bits to decimal, and subtracts one. This number is used as an index, and appends the corresponding word from bip39 in an array called mnemonic.
  4. No matter what, the code will always print “Wrong”! :D

Let’s write a simple script to find the mnemonics with this information:

mnemonic.py
#!/usr/bin/python3
words = []


with open('bip39list.txt', 'r') as f:
    words = f.read().splitlines()


code = 75673125099835840306362297188218306412669859836254678874904603942583570317024638985472
code = bin(code)[2:]
code = str(code.zfill(len(code) + (12 - len(code) % 12)))


mnemonic = []


for i in range(0, len(code), 12):
    mnemonic.append(words[int(code[i:i + 12], 2) - 1])


print(mnemonic)

Running the script:

Terminal window
$ python3 mnemonic.py
['evidence', 'leopard', 'solution', 'layer', 'legend', 'danger', 'orient', 'project', 'silver', 'flower', 'wrong', 'path', 'stove', 'throw', 'fortune', 'report', 'nuclear', 'old', 'target', 'exact', 'broom', 'hawk', 'toss', 'paper']

Looks like we’ve got our mnemonic!

Now we can visit MyEtherWallet and enter the 24-word mnemonic phrase. Look for the 0xACa5872e497F0Cc626d1E9bA28bAEC149315266e wallet and gain access to the dashboard:

MEW dashboard

To access the private key, go to My personal account -> View paper wallet:

Viewing wallet

The flag is SEKAI{0x81c458e9fae445de18385a3379513acc8e191e4c2667c85aa0a52a32ec4e6d55}.