HTB Starting Point - Impacket : unpack requires a buffer of 1 bytes

joserick1532 · December 2, 2020, 11:16pm

Hello guys, I’m new in htb and infosec,
I started with the initial VM ( starting point) and I got an error when trying to connect to mssql, after entering passwd it shows:

"[-] (‘unpack requires a buffer of 1 bytes’, “When unpacking field ‘Type | <B | b’’[:1]’”)

which I don’t understand what it means.

I tried the option of :

mssqlclient.py ARCHETYPE/sql_svc@10.10.10.27 -windows-auth
with password: M3g4c0rp123

Some helpfull info ( I hope):

I installed the package from the blackarch repo with "sudo pacman -S impacket " (0.9.21-1)
, I also tried with the package from github (0.9.22) and got the same response …
Other thing that I noticed is when running the Nmap scanning the port of mysql seemed tcpwrapped, so I don’t know iof this can be part of the issue.
Also tried running the command with -debug

And found this (but dunno how to interpret it)

File “/home/user/.local/lib/python3.8/site-packages/impacket/structure.py”, line 282, in unpack return unpack (format,data)[0]

Thanks for the help and for your time .

snowdroppe · December 3, 2020, 12:50pm

Hey there,

I’m in your exact same position - just getting into HTB myself. I experienced the exact same issue you did and attempted the same solutions.
I delved into “structure.py” and the exception is raised because structure.py is passed an empty byte (b’’) from tds.py. I tried patching line 83 in structure.py to:

if data is not None and len(data) > 0

just in case it was an oversight (unlikely) but it didn’t help - it resulted in a different error:

$ python3 ./mssqlclient.py ARCHETYPE/sql_svc@10.10.10.27 -windows-auth -debug 
Impacket v0.9.22 - Copyright 2020 SecureAuth Corporation

[+] Impacket Library Installation Path: /usr/lib/python3/dist-packages/impacket
Password:  [M3g4c0rp123]                                                                                                
[+] Exception:                                            
Traceback (most recent call last):
  File "./mssqlclient.py", line 179, in <module>          
    res = ms_sql.login(options.db, username, password, domain, options.hashes, options.windows_auth)
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 905, in login
    resp = self.preLogin()
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 520, in preLogin 
    tds = self.recvTDS()
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 607, in recvTDS
    status = packet['Status']     
  File "/usr/lib/python3/dist-packages/impacket/structure.py", line 166, in __getitem__
    return self.fields[key]                                                                                          
KeyError: 'Status'                                                                                                   
[-] 'Status'

My suspicion is that something is up with the MSSQL database if someone higher up could check that claim? This is compounded by 90% of authentication requests resulting in the socket being closed by the remote host and resulting in:

$ python3 ./mssqlclient.py ARCHETYPE/sql_svc@10.10.10.27 -windows-auth -debug 
Impacket v0.9.22 - Copyright 2020 SecureAuth Corporation
                                                                                                                     
[+] Impacket Library Installation Path: /usr/lib/python3/dist-packages/impacket
Password:  [M3g4c0rp123]                                                                                                  
[+] Exception:                                            
Traceback (most recent call last):
  File "./mssqlclient.py", line 179, in <module>          
    res = ms_sql.login(options.db, username, password, domain, options.hashes, options.windows_auth)
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 905, in login
    resp = self.preLogin()
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 520, in preLogin 
    tds = self.recvTDS()
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 606, in recvTDS
    packet = TDSPacket(self.socketRecv(packetSize))
  File "/usr/lib/python3/dist-packages/impacket/tds.py", line 586, in socketRecv
    data = self.socket.recv(packetSize)                                                                              
ConnectionResetError: [Errno 104] Connection reset by peer                 
[-] [Errno 104] Connection reset by peer

grayhaze · December 3, 2020, 1:02pm

Hi guys, I’m struggling with this too at the moment. I also tried to use version 0.9.19 of Impacket which is the same as is being used in the tutorial. This I tried in both python 2 and 3 virtual environments, but the error persists.

zaltan · December 3, 2020, 1:19pm

Yup having the same issue I tried everything possible but nothing still get this error.

renysh · December 3, 2020, 4:53pm

Hello…
I have the same error,

snowdroppe · December 3, 2020, 5:29pm

Raised a ticket with the service desk, will update when I hear back

Ruhf · December 3, 2020, 8:22pm

I am also having the same problem. First time I tried it and got [-] (‘unpack requires a buffer of 1 bytes’, “When unpacking field ‘Type | <B | b’’[:1]’”) Then I tried command again and now I’m getting [-] [Errno 104] Connection reset by peer

jackaltx · December 3, 2020, 10:03pm

just starting…same issue. Heres a trace

─$ impacket-mssqlclient -windows-auth “ARCHETYPE/sql_svc@10.10.10.27” -debug
Impacket v0.9.23.dev1+20201203.125520.aa0c78ad - Copyright 2020 SecureAuth Corporation

[+] Impacket Library Installation Path: /usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket
Password:
[+] Exception:
Traceback (most recent call last):
File “/usr/share/doc/python3-impacket/examples/mssqlclient.py”, line 179, in
res = ms_sql.login(options.db, username, password, domain, options.hashes, options.windows_auth)
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/tds.py”, line 905, in login
resp = self.preLogin()
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/tds.py”, line 520, in preLogin
tds = self.recvTDS()
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/tds.py”, line 606, in recvTDS
packet = TDSPacket(self.socketRecv(packetSize))
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/structure.py”, line 84, in init
self.fromString(data)
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/structure.py”, line 149, in fromString
self[field[0]] = self.unpack(field[1], data[:size], dataClassOrCode = dataClassOrCode, field = field[0])
File “/usr/local/lib/python3.8/dist-packages/impacket-0.9.23.dev1+20201203.125520.aa0c78ad-py3.8.egg/impacket/structure.py”, line 382, in unpack
return unpack(format, data)[0]
struct.error: (‘unpack requires a buffer of 1 bytes’, “When unpacking field ‘Type | <B | b’’[:1]’”)
[-] (‘unpack requires a buffer of 1 bytes’, “When unpacking field ‘Type | <B | b’’[:1]’”)

I am using Kali 2020.2 distro where I have gottent the latest impacket from github

impacket-mssqlclient -h 130 ⨯
Impacket v0.9.23.dev1+20201203.125520.aa0c78ad - Copyright 2020 SecureAuth Corporation

─$ python3 --version
Python 3.8.6

Suggestions ???

bearscat · December 4, 2020, 3:08am

I have the same error too, i thought it was just me until i looked here. Seems we need to wait for a fix on the starting point machine?

MasKeo13 · December 4, 2020, 8:04am

I recently got into HTB and I am also stuck and running into this issue.

frothycoffee · December 4, 2020, 4:36pm

did anyone find a solution as its driving me crazy. im asuming not or someone would have commented

snowdroppe · December 4, 2020, 6:15pm

I have a ticket open and the service desk is working through it. In the meantime, I recommend the academy

frothycoffee · December 4, 2020, 8:12pm

THANKS for the reply please post result as ive just finished reinstalling kali removing reinstalling impacket python2 python3 added few versions of impacket all return the same
“[-] (‘unpack requires a buffer of 1 bytes’, “When unpacking field ‘Type | <B | b’’[:1]’”)”
or
“[-] [Errno 104] Connection reset by peer”

FunnyManMitch · December 5, 2020, 9:21pm

Type your comment> @snowdroppe said:

I have a ticket open and the service desk is working through it. In the meantime, I recommend the academy

Let us know what they say

TheRedW1z4rd · December 6, 2020, 11:17pm

Thank you, I thought I was going mad.

zvikam · December 7, 2020, 5:22am

same issue here.
tried to follow some ideas I found in this forum, nothing worked.
updated all PIP packages, tried Python 3.7 - all the same.

are we all using the latest Kali VM?
I thought I’d try an older ubuntu docker just to rule it out…

r00tb0xm0d1 · December 7, 2020, 5:42am

Try modifying your command to include the password like so:
mssqlclient.py ARCHETYPE/sql_svc:M3g4c0rp123@10.10.10.27 -windows-auth

snowdroppe · December 7, 2020, 10:06am

The problem was definitely server side and has now been resolved by service desk. You may still need to update Impacket if you get digest errors (tested and working with 0.9.22).

shadow2sniff · December 7, 2020, 1:45pm

same issue here

Tried in both Kali and Parrot os also tried with Python2.7, Python3.8. Not working.

zvikam · December 7, 2020, 7:40pm

tested and working, indeed!