US20090006424A1 - System, method and program product for determining if a user has received a redirected web page - Google Patents

Abstract

System, method and program product determine redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application. A first URL is sent to the application, and in response, a first web page is received from the application. A second URL is created by appending one or more characters to the first URL. The second URL is unrecognizable by the application. A request for the second URL is sent to the application, and in response, a second web page is received. The content of the second web page is compared to the content of the first web page. If the content of the second web page matches the content of the first web page, a record is made indicating that the first web page is a redirected web page.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application is a continuation of patent application Ser. No. 11/122,663, filed May 5, 2005, entitled System, Method and Program Product for Determining if a User has Received A Redirected Web Page, the entirety of which is incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• n/a
FIELD OF THE INVENTION
• The present invention relates generally to a method, system and computer program product for determining whether a web browser user has received a redirected web page, and more specifically, to a method, system and computer program product for determining redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application.
BACKGROUND OF THE INVENTION
• The World Wide Web (“WWW”) is well known today. Users of client computers with web browsers request web pages by specifying a URL, either by typing the URL into an address field or selecting a link for a URL. Typically, the user requests the web page using HTTP. Web pages are often a user interface to an application hosted by a server and contain information, such as product information, related to the application. Such web pages often include links to access other web pages or invoke services of the application. Other web pages are merely informational, and do not provide an operational interface to any application.
• In response to a user request for a web page (where the user request specifies a URL), the user's web browser obtains from a domain name server (“DNS”) an IP address of a server and application on the server represented by the URL. Then the web browser forwards the client request for the web page to the (IP address of the) server/application. In response, the requested application on the server returns the requested web page, and a return code of “2xx” indicating that the requested web page was successfully located and returned.
• Occasionally, the server or application addressed by the user-specified URL redirects the user request to another server and/or application which returns a “redirected” web page (not the one represented by the user-specified URL). For example, a user may request a web page for a presumed URL based on a generic product name, and a proxy server listed in a domain name server as responsible for that URL will redirect that request to another server and application which provides information or services relating to the generic product. As another example, a vulnerability scanning tool can simulate requests made by a person outside of a firewall or an enterprise being tested to determine if the person can access sensitive web pages from an application within the firewall or enterprise being tested. If so, this represents a security “hole.” If not, the server and application addressed by the tool will redirect the request to a default URL which returns a “Sorry, Page Not Found” web page and a return code other than “2xx” to indicate that the returned page was not the one requested. As another example, if a hyperlink requested by a user is not functioning, the server executing the connection may redirect the user to a web page indicating a request was not successful. As another example, a load balancer or network dispatcher which receives a user request for a URL that does not exist or is not accessible may redirect the user request to a default “page not found” web page.
• When a server returns a web page other than the one requested by the user, i.e. other than the one represented by the user-specified URL, the server typically provides with the web page a return code other then a “2xx.” An RFC2068 industry standard defines five classifications for HTTP return codes: A “1xx” return code means that the server to which the request was sent is processing the request. A “2xx” return code means that the request was successfully received, understood and accepted. A “3xx” return code means that the request was redirected, and a user must take further action to complete the request such as to wait or to select another link on a redirection web page. A “4xx” return code means a client error such as bad syntax, and cannot be fulfilled. A “5xx” return code means a server error such that the server failed to fulfill an apparently valid request. However, the application which returns the redirected web page may be programmed to return a different return code for a variety of reasons. For example, the application which returns the redirected web page with the misleading return code may want to abstract or conceal the fact that the user request was redirected or may have a valid security reason for concealing the redirection. In many cases, the redirected web page does not indicate anywhere else in the web page that the web page is redirected. In other cases, the application which returns the redirected web page may be programmed to return a web page such as illustrated inFIG. 1 which does not include the proper “404” return code, but clearly states in text that the requested web page was not found. Even though this web page indicates in text that the web page was not found, if the requester is a program tool looking for a return code, then the program tool will not recognize this web page as redirected.
• There are various situations where the user needs to know that the web page which was returned was not the one requested. In some of these cases the “user” is a person, and in other cases the “user” is a program executing on the user's workstation. For example, consider when the foregoing vulnerability scanning tool simulates requests made by a person, and the application addressed by the tool recognizes the tool as not authorized to access the web page. In such a case, instead of returning the sensitive web page, the addressed application redirects the request to a default application which returns a “Sorry, Page Not Found” web page. If the default application does not return the industry standard “404” code (representing “page not found”), the vulnerability scanning tool may interpret the redirected web page as the one requested by the tool, and conclude that the sensitive web page was returned and a “hole” exists in the security system.
• FIG. 2 illustrates another type of known redirected web page. The user-requested application has redirected the user request to a known “time-out” application (because the user's connection to the user-requested application has timed-out). The time-out application returns a redirected web page requesting the user to logon again, instead of the web page to interface to the requested application. Even though this is a redirected web page, the “time-out” application included a “252” (non-redirected) status return code in the URL field: http://129.33.31.252/cgi-bin/ctguests.idc. Consequently, if the “user” is the foregoing vulnerability scanning tool, the tool may interpret this web page as the one originally requested by the tool, calculate that the web page was returned after the expiration of the time-out period, and conclude that a “hole” exists in the security system.
• Therefore, a need exists to enable a web browser or associated program to better detect when a user request for a web page has been redirected.
SUMMARY OF THE INVENTION
• The present advantageously provides a system, method and computer program product for determining for determining redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application. Generally, a web page received from an application is deemed a redirected web page if the content of the original web page matches the content of a second web page returned in response to sending the application an altered URL.
• In accordance with one aspect of the present invention, a method is provided for determining redirection of a URL sent by a web browser to an application. A first URL is sent to the application, and in response, a first web page is received from the application. A second URL is created by appending one or more characters to the first URL. The second URL is unrecognizable by the application. A request for the second URL is sent to the application, and in response, a second web page is received. The content of the second web page is compared to the content of the first web page. If the content of the second web page matches the content of the first web page, a record is made indicating that the first web page is a redirected web page.
• In accordance with another aspect of the present invention, a system for determining redirection of a URL includes an application, a web browser, and a processor. The web browser is communicatively coupled to the application and the processor. The web browser operates to send a first URL to the application, and in response, receive a first web page from the application. The web browser further operates to send a request to the application for a second URL, the second URL being unrecognizable by the application, and in response, receive a second web page. The processor operates to create the second URL by appending one or more characters to the first URL. The processor further operates to compare content of the second web page to content of the first web page, and if the content of the second web page matches the content of the first web page, make a record indicating that the first web page is a redirected web page.
• In accordance with yet another aspect of the present invention, a computer program product for determining redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application includes program instructions stored on a computer readable medium. The first program instructions send a first URL to the application, and in response, receive a first web page from the application. The second program instructions create a second URL by appending one or more characters to the first URL. The second URL is unrecognizable by the application. Third program instructions send a request to the application for the second URL, and in response, receive a second web page. Fourth program instructions compare the content of the second web page to the content of the first web page. If the content of the second web page matches the content of the first web page, fifth program instructions make a record indicating that the first web page is a redirected web page.
BRIEF DESCRIPTION OF THE DRAWINGS
• A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
• FIG. 1 is a redirected web page according to the Prior Art.
• FIG. 2 is another redirected web page according to the Prior Art.
• FIG. 3 is a block diagram of a user workstation which includes a web browser according to the prior art, and a web page analysis program according to the present invention.
• FIG. 4 is a flow chart of the web page analysis program ofFIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
• The present invention will now be described in detail with reference to the figures.FIG. 3 illustrates a user'sworkstation10 which includes aweb browser12 such as Microsoft Explorer or Netscape Navigator web browser.Web browser12 includes the known functions of requesting web pages based on a user-specified URL and receiving and displaying the returned web pages.Workstation10 also includes a webpage analysis program13 according to the present invention to determine whether the returned web page is the one requested by the user or whether the returned web page is instead a redirected web page.Workstation10 also includes a knownCPU14 to executeweb browser12 andweb analysis program13, aRAM16, aROM18,disk storage20 and a TCP/IP interface21 to theInternet22.Workstation10 is coupled viaInternet22 to aserver32.Server32 includes a knownCPU44,RAM46,ROM48 anddisk storage50.CPU44 executes anapplication program34 requested by a user ofworkstation10. The user ofworkstation10 may request a web page fromapplication34 by specifying aURL representing application34 and the web page.Server32 also includes a redirectedapplication program36 which supplies to the user at workstation10 a redirected web page, whenapplication34 redirects the user request toapplication program36. There are many possible reasons whyapplication34 redirects the user request toapplication36. For example, the user may have requested an application by a generic name, and there is no such application at the user-specified URL. As other examples, the user may have requested a sensitive web page which the user is not allowed to access, or the user's session with the user-specified application may have timed-out. The reason for the redirection is not part of the present invention.
• As noted above,program13 determines whether the web page which is returned to the user is the one requested by the user or is instead, a redirected web page.FIG. 4 illustrates the webpage analysis program13 in more detail. Instep100,program13 fetches the returned web page from memory or storage ofworkstation10. Typically, the web page is in HTML form with text fields and image fields enclosed by respective symbols.Program13 can be used to analyze all returned web pages or only those of concern. For example, theworkstation10 can execute a vulnerability scanning program tool19. Tool19 identifies several returned web pages as sensitive web pages which should not have been returned, i.e. security “holes.” In such a case,program13 can be invoked to test these returned web pages to determine whether they are the requested web pages, in which case they represent security “holes,” or whether they are redirected web pages, in which case they do not represent security “holes.”
• Next,program13 scans the text within the HTML for commonly used text phrases found on redirected web pages (step102). For example, such text can be “page not found,” “page does not exist,” or “bad request.”Program13 obtains a list of such commonly used text phrases from afile104 withinRAM16. If one of the text phrases stored infile104 is found on the returned web page (decision104, yes branch), thenprogram13 concludes that the returned web page is a redirected web page (step106). However, if one of the text phrases stored infile104 is not found (decision104, no branch), thenprogram13 creates a “dummy” URL by adding a bogus text extension to the URL of the returned web page (step110). The bogus text extension comprises text that is not likely to match any real application, such as “NoWayThisPageExists.” (The actual character string is not important as long as it is not likely to match a real application.) For example, if the URL of the returned web page is “http:/www.IBM.com,” then the “dummy” URL can be “http:/www.IBM.com/NoWayThisPageExists.”Program13 forwards the dummy URL toweb browser12 when requests the corresponding web page. The same application which returned the web page will likely receive the dummy URL because the dummy URL has the same beginning as that of the returned web page. However, the application which returned the web page will not likely recognize the extension. Consequently, the application which returned the web page will redirect the request to a default application which handles improperly addressed URLs. This default application, which may be the same as the application which returned the web page, will return a redirected web page. Then,program13 will compare the text and graphics in the redirected web page returned by the default application to the text and graphics in the web page returned earlier (step120). If they are the same (decision122, yes branch), thenprogram13 concludes that the web page returned earlier was a redirected web page (step106). It should be noted that if the originally returned web page includes a graphical drawing of “Page Not Found” or a text phrase which is not included infile106 but nevertheless indicates a redirection, this will not be detected instep102, but will be detected instep120. Referring again todecision122, no branch where the two web pages are not the same, then theprogram13 concludes that the web page returned earlier was not a redirected web page (step126). It is possible that there are two or more different redirected web pages for the originally specified application, and the dummy URL may return a different redirected web page than the redirected web page that was originally returned. In such a case,program13 will conclude that the web page that was originally returned was not redirected, which is incorrect. Nevertheless, in most cases, there is only one redirected web page for each user-specified URL. So, when the web page that was originally returned does not match the one returned from the dummy URL, it is likely that the web page that was originally returned was the one requested by the user, and not a redirected web page. For those applications where the present invention is used to check whether unauthorized/sensitive web pages have been returned to a vulnerability checking tool,program13 can identify as redirected (and therefore, not security violations) most of the web pages identified by the vulnerability checking tool as unauthorized security violations. So, the present invention will reduce the number of web pages that an operator will need to check manually.
• Webpage analysis program13 can be loaded intoworkstation10 from a computer storage medium such as magnetic disk, CD-ROM or DVD, or downloaded from theInternet22 via TCP/IP interface21.
• Based on the foregoing, a system, method and program product have been disclosed for determining if a web page returned to a web browser is a redirected web page. However, numerous modifications and substitutions can be made without deviating from the scope of the present invention. Therefore, the present invention has been disclosed by way of illustration and not limitation, and reference should be made to the following claims to determine the scope of the present invention.

Claims (20)

1. A method for determining redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application, said method comprising the steps of:

sending a first URL to said application, and in response, receiving a first web page from said application;

creating a second URL by appending one or more characters to said first URL, said second URL being unrecognizable by said application;

sending a request to said application for said second URL, and in response, receiving a second web page;

comparing content of said second web page to content of said first web page; and

responsive to determining that said content of said second web page matches said content of said first web page, making a record indicating that the first web page is a redirected web page.

2. The method as set forth inclaim 1, further comprising the steps of:

responsive to determining that said content of said second web page does not match said content of said first web page, making a record indicating that said first web page was not determined to be a redirected web page.

3. The method as set forth inclaim 1, wherein said one or more characters are chosen such that said second URL is not likely to be recognized by said application.

4. The method as set forth inclaim 1, wherein the comparing step comprises comparing text of said second web page to text of said first web page.

5. The method as set forth inclaim 4, wherein the comparing step further comprises comparing graphics of said second web page to graphics of said first web page.

6. The method as set forth inclaim 1, wherein the comparing step comprises comparing graphics of said second web page to graphics of said first web page.

7. The method as set forth inclaim 1, further comprising the step of scanning content of said first web page for a text phrase indicative of a redirected web page.

8. The method as set forth inclaim 7, wherein said text phrase indicative of a redirected web page includes at least one of “page not found,” “page does not exist,” “bad request” and “404”.

9. A system for determining redirection of a Uniform Resource Locator (“URL”), said system comprising:

an application;

a web browser communicatively coupled to the application, the web browser operating to:

send a first URL to said application, and in response, receive a first web page from said application; and

send a request to said application for a second URL, said second URL being unrecognizable by said application, and in response, receive a second web page; and

a processor communicatively coupled to the web browser, said processor operating to:

create said second URL by appending one or more characters to said first URL;

compare content of said second web page to content of said first web page; and

responsive to determining that said content of said second web page matches said content of said first web page, make a record indicating that the first web page is a redirected web page.

10. The system as set forth inclaim 9, wherein responsive to determining that said content of said second web page not match said content of said first web page, said processor is further operable to make a record indicating that said first web page was not determined to be a redirected web page.

11. The system as set forth inclaim 9, wherein said one or more characters are chosen such that said second URL is not likely to be recognized by said application.

12. The system as set forth inclaim 9, wherein the processor compares text of said second web page to text of said first web page.

13. The system as set forth inclaim 12, wherein the processor further operates to compare graphics of said second web page to graphics of said first web page.

14. The system as set forth inclaim 9, wherein the processor further operates to scan content of said first web page for a text phrase indicative of a redirected web page.

15. The system as set forth inclaim 14, wherein said text phrase indicative of a redirected web page includes at least one of “page not found,” “page does not exist,” “bad request” and “404”.

16. A computer program product for determining redirection of a Uniform Resource Locator (“URL”) sent by a web browser to an application, said computer program product comprising program instructions stored on a computer readable medium, the program instructions comprising:

first program instructions to send a first URL to said application, and in response, receive a first web page from said application;

second program instructions to create a second URL by appending one or more characters to said first URL, said second URL being unrecognizable by said application;

third program instructions to send a request to said application for said second URL, and in response, receive a second web page;

fourth program instructions to compare content of said second web page to content of said first web page; and

responsive to determining that said content of said second web page matches said content of said first web page, fifth program instructions to make a record indicating that the first web page is a redirected web page.

17. The computer program product as set forth inclaim 16, wherein said one or more characters are chosen such that said second URL is not likely to be recognized by said application.

18. The computer program product as set forth inclaim 16, further comprising responsive to said content of said second web page not matching said content of said first web page, sixth program instructions to make a record that said first web page was not determined to be a redirected web page.

19. The computer program product as set forth inclaim 16, further comprising sixth program instructions to scan content of said first web page for a text phrase indicative of a redirected web page.

20. The computer program product as set forth inclaim 19, wherein said text phrase indicative of a redirected web page includes at least one of “page not found,” “page does not exist,” “bad request” and “404”.

Images