Patent Publication Number: US-2007124389-A1

Title: Anti-spam application storage system

Description:
TECHNICAL FIELD  
      This invention relates to arrangements for long term storage of short message system (SMS) messages.  
     BACKGROUND OF THE INVENTION  
      With the advent of the Internet, it has become easy to send messages to a large number of destinations at little or no cost to the sender. The same is true of short message service (SMS). These messages include unsolicited and unwanted messages (spam) which are a nuisance to the receiver of the message who has to clear the message and determine whether it is of any importance. Further, it is a nuisance to the carrier of the telecommunications network used for transmitting the message, not only because it presents a customer relations problem with respect to irate customers who are flooded with spam, but also because these messages, for which there is usually little or no revenue, use network resources. An illustration of the seriousness of this problem is given by the following two statistics. In China in 2003, two trillion short message service (SMS) messages were sent over the Chinese telecommunications network; of these messages, an estimated three quarters were spam messages. The second statistic is that in the United States an estimated 85-90% of e-mail messages are spam.  
      These spam messages are not merely a nuisance, but are in many instances a means for defrauding the recipients of the message by making it apparently attractive for them to provide their credit card information or by urging them to send in a modest amount of money (for “processing expenses” or “taxes”) in the expectation of receiving a very much larger amount. Messages, automatically originated by a computer, for defrauding are frequently sent to a very large number of destinations in the hope that at least some of these destinations will be foolish enough to respond. The problem is serious in the United States but is actually acute in China, Japan, Korea, and, to a lesser extent, in Europe. These latter countries typically have an enormous volume of SMS messages.  
      In order to identify and prosecute such fraudulent use of telecommunications services, it is desirable to be able to record the messages which are used for perpetrating such frauds. In order to be useful for analysis purposes, it may be necessary to keep such messages for an extended retention period—months or perhaps years. A problem of the prior art is that the number of messages which are generated each retention period is far greater than the number of messages which can be stored for a reasonable cost.  
     SUMMARY OF THE INVENTION  
      The above problem is greatly alleviated and an advance is made over the prior art in accordance with this invention wherein a filtration system is used to control the recording of different SMS messages into ones of a plurality of subfiles of a storage system; each subfile contains a different type of message such as black list messages, ambiguous messages, white list messages, messages from a highly suspect source; for each subfile, a system administrator can control the percentage of messages to be stored in the subfile and the duration of time that these messages are to be stored. Advantageously, with this arrangement, the administrator or a telecommunications system can control the volume and category of stored messages.  
      In accordance with one feature of Applicants&#39; invention, if, for a particular source, messages are analyzed to be mass delivered, then only a single copy is stored, along with an optional count of the number of such messages.  
      In accordance with another feature of Applicants&#39; invention, different sub-directories can be stored in different types of memories so that those categories which have to be examined frequently, such as messages from highly suspect sources, are in a more accessible type of memory.  
      In accordance with another feature of Applicants&#39; invention, different sub-directories can be accessed according to different access privileges. Examples of subfiles which would require special access are security sensitive subfiles, anti-spam analysis for self-training subfiles. 
    
    
     BRIEF DESCRIPTION OF DRAWING(S)  
       FIG. 1  is a block diagram illustrating the operation of Applicants&#39; invention;  
       FIG. 2  is a flow diagram illustrating the operation of Applicants&#39; invention;  
       FIG. 3  is a layout of a typical anti-spam storage file and its subfiles; and  
       FIG. 4  is a flow diagram illustrating the use of an Administrative System to control the operation of Applicants&#39; invention. 
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a block diagram illustrating the operation of Applicants&#39; invention. SMS messages come to an anti-spam application  101 , a software process running on an appropriate computer, whose purpose is to filter out spam messages. Examples of anti-spam applications are the MiLife SMS Anti-Spam Application available from Lucent Technologies Inc., and the Nexus NETVIEW Signaling Survey System. The output of the anti-spam application  101  includes non-spam messages  121 ; ambiguous messages  123  which cannot be identified as spam or non-spam messages in the first stage filtering, but can be forwarded to a second stage, anti-spam application  102 , for deep analysis to determine whether they are good or spam messages; and spam messages  125 . For messages  125  the anti-spam application  101  has a strong indication that it is a spam message and that the message should not be delivered to the destination. For example, messages  125  include messages from one of a black list of sources from which the destination does not wish to accept messages. Examples of non-spam messages  121  are messages whose source is on a white list of the destination as representing sources acceptable to the message destination. Ambiguous messages are messages whose source is neither on the white list nor on the black list but for which there are other indications that the message is not clearly a non-spam message. For example, when an Anti-Spam filter engine such as anti-spam application  101  does content or key word analysis and the result shows a spam severity index that is medium, then the message will be forwarded to the second stage for deep analysis; if the second stage analysis engine still cannot justify whether it is spam, it will treat such messages  131  as good messages to be delivered to the destination, or send such messages to an operator to manually check the spamness, and option to store in the storage system.  
      Messages  121 ,  125 ,  127 ,  129  and  131  are sent to storage control system  103  for storage in one of the subfiles ( 302 , . . . ,  368 ) of the storage system  300 . Both good and spam messages are stored, but different percentages and different retention intervals are generally assigned to these different messages.  
      An administrative system  105  is used to provide control information to the storage control system. The control information can be information such as the percentage of messages destined for a particular subfile which should be stored, the subfile destination of different categories of messages (e.g., messages from certain sources destined for a common subfile) and information to control the duration of storage of messages in each of the subfiles. Effectively, the administrative system controls the rules that the storage control system uses to decide which messages should be stored and to decide which subfile should be used for storing each such message.  
       FIG. 2  is a flow diagram illustrating the operation of Applicants&#39; invention. An anti-spam application (ASA)  101  and a second stage ASA  102  receive incoming SMS messages (action block  201 ). The ASA and second stage ASA categorize these messages according to spam type (action block  203 ). Major categories of messages are shown in  FIG. 3 .  
      The ASA and second stage ASA pass these categorized messages to the storage control system (SCS) (action block  205 ). The storage control system then further categorizes messages according to the subfile in storage system in accordance with the rules stored for the storage control system (action block  207 ). For example, the storage control system may have one category for messages from a particularly suspicious source. The advantage of this further categorization is that while ordinary spam messages may be saved only to the extent of, for example, 25%, these messages from highly suspicious sources may be saved 100%. Also, they are saved in a separate subfile to allow for special access from an administrative system for examining these messages. Special subfiles can be set up for individual ones of these suspicious sources. The further categorization carried out by the storage control system is performed in accordance with rules supplied by an administrative system.  
      The storage control system decides whether a specific message ought to be stored (action block  209 ). Since it would be impractical to store all messages, only a fraction of messages is stored. The fraction is a function of the particular subfile in which the messages are to be stored. The fractional allotment is carried out by either storing N out of every M messages for a fraction of N/M or by some process which randomizes the selection of the message to be stored. An example of a randomizing process is one which examines the last few digits of the clock and performs the storage or non-storage function in accordance with the reading of that clock.  
      The storage control system then passes messages to be stored including an identity of the subfile to the storage system (action block  211 ). The storage system then stores the passed messages (action block  213 ).  
      In accordance with one preferred embodiment of the invention, the retention interval is customized for each subfile or group of subfiles (action block  215 ).  
       FIG. 3  is a sample data layout showing a typical complete anti-spam storage file  300  including a set of good short message service (SMS) subfiles  302 , a set of spam SMS subfiles including a set of mobile originating spam subfiles  306 , and a set of mobile terminating spam SMS subfiles  308 . Included in the good short message system subfiles are intra-network good SMS subfiles  320 ; inter-network good SMS subfiles  322  and subfiles used for self training purposes to help identify future good SMS subfiles  324 .  
      The mobile originating spam subfiles include intra-network spam subfile  330 , inter-network spam SMS subfile  332 , roaming mobile origination spam subfiles  334 , finance fraud SMS subfile  336 , and pornography SMS subfiles  338 . These subfiles are used to help identify originators of spam SMS subfiles.  
      Mobile terminating spam SMS subfiles include spam from identified source network subfiles  350 , flooding or mass distributed spam subfiles  352 , spoofing spam subfiles  354 , spam subfiles with a fake source address  356 , pornography spam subfiles  358 ; finance fraud spam subfiles  360 , spam subfiles for gun sales  362 , intra-network spam subfiles  364 , potential crime spam subfiles  366 , and illegal advertising spam subfiles  368 . For each subfile, a count is maintained of the number of messages and the date and time of each entry. For each subfile, a tentative allotment of space has been initialized and the percentage fill of each subfile is maintained. For each subfile, a percentage of messages of the appropriate kind to be stored in the subfile is maintained; for many of the subfiles, especially the subfiles for fraudulent spam messages, the percent of messages to be stored is frequently 100%. For each subfile, a retention period is maintained so that the older messages are cleared to make room for new messages.  
      As can be seen from the example, some subfiles apply only to mobile terminating or to mobile originating traffic. In alternative layouts, the same subfile can be used for both directions of traffic. The subfile system can be customized to meet the needs of each telecommunications carrier or application.  
      Different subfiles can have different and/or a plurality of thresholds for notifying the administrative system that the subfile is sufficiently close to being full so as to require some action to delete messages or increase the size of the subfile.  
       FIG. 4  is a flow diagram illustrating the operation of the administrative system for controlling the storage of messages. The administrative system (AS) accesses data in the storage system (action block  401 ). The administrative system may access this data in order to ascertain the fill of each or any of the subfiles and/or to obtain specific data of messages stored in a subfile.  
      Based on the accessed data, the administrative system modifies the rules of the storage control system (action block  403 ). For example, if the administrative system finds that the fill of a non-spam subfile is relatively high, the administrative system may modify the rule for storing messages destined for that subfile to reduce the fraction that will be stored. For example, during a holiday season, many more non-spam greeting messages may be sent. The retention fraction would be lowered to accommodate this flurry of traffic.  
      The administrative system then transmits the modified rules to the storage control system (action block  405 ) which performs its function in accordance with the modified rules.  
      The staff of the administrative system can be given restrictive access to the contents of the storage system. For example, special passwords may be required to access the finance fraud subfile, to prevent an insider from warning a thief.  
      The above description is of one preferred embodiment of Applicants&#39; invention. Other embodiments will be apparent to those of ordinary skill in the art. The invention is limited only by the attached claims.