TweetFollow Us on Twitter

Virus Protection
Volume Number:8
Issue Number:2
Column Tag:Pascal Workshop

Related Info: Resource Manager

Simple Antivirus Protection

An anti-virus scheme that can be painlessly added to every application.

By Nicholas Pisarro, Jr., Westport, Connecticut

About the author

Nick Pisarro is the principle architect of Aperture Visual Information Manager by the Graphic Management Group, Inc. He has been involved with all aspects of computer design including both hardware and software since 1961 and with the Macintosh since 1986.

The Virus Scout Pascal unit described in the January 1991 Programmer’s Forum is a nice idea. One problem with Virus Scout was that it was coded to handle only those specific viruses that the author knew about and could offer no protection against any future viruses that may infect an application.

It did set me to wondering, however, if there is a way to make both a simpler yet more universal virus detection scheme. I began to think about how viruses infect and reproduce themselves through an application, and how I could have applications I have developed protect themselves from becoming infected.

In order for a virus to infect an application it needs to either modify the existing resources of an application and/or add resources of its own. In order to reproduce it needs to seize program control from the application and the user’s Macintosh in order to issue its own instructions of death and destruction. This requires modification of a code resource such as ‘CODE’, ‘WDEF’, ‘MDEF’, or ‘LDEF’ resource types.

Usually a virus inserts a small stub of code in an existing resource to branch to one of its own resources, or it inserts a whole new code resource of its own to seize control. I don’t believe any viruses try to insert all their code in an existing application resource but always have to add a resource. Adding to a code resource, by linking in code, is a difficult operation and runs the risk of overflowing the size restrictions of code resources.

One advantage a virus detection scheme has within an application is that it knows how many and what types of resources the application should have! Rather than checking for the addition of specific virus resources, the virus detection scheme presented here just checks the number of resources the application should have against the number it actually has. In addition there is a Toolbox call that tells me the number of types of resources a resource fork has as well as specific counts. This may be used to check for the addition of additional types of resources. As the resource map for an application is in memory when it is running these types of checks do not use significant amounts of computer time.

It would be possible to check counts of all the resource types an application has, but I believe just checking the specific counts of its code resources is sufficient. A virus must insert or modify a code resource to gain control.

The Pascal unit here reads a resource with a count of the number of types of resources an application has as well as counts of specific types. If it finds any mismatch between expectations and reality, it notifies the user and causes the application to quit early. Note the “Get1” form of the resource call is used to get counts only from this application. This unit must be run before any data file resource forks are opened. If the application modifies its own resource fork, it must be careful not to do it in a way that triggers this virus check.

In the sample code no specific resource type has been assigned for the information resource. If all applications used the same type for this resource, a new virus could be written to circumvent this protection scheme. Use your own type.

Note that the code here is only concerned with viruses that infect an application, rather than viruses that infect files in the System Folder or the Desktop. Code like that from Virus Scout or elsewhere could be added to do this additional checking.

Listing

{Written by Nicholas Pisarro, Jr., Aperture Technologies, Inc.
 No rights reserved.}

UNIT VirusCheck;

INTERFACE

USES
 {$LOAD}
 MemTypes, QuickDraw, OSIntf, ToolIntf, PackIntf;
 

{Returns TRUE if Application can run.}
FUNCTION ApplicationCanRun: BOOLEAN;


IMPLEMENTATION

{Returns TRUE if Application can run.}
FUNCTION ApplicationCanRun: BOOLEAN;
 CONST
 kVirusChkKinds  = '????';{Rsrc type for the # 'CODE' & # of Kinds of 
resources}
 kVirusChkID=  32; {Resource ID for the Virus Check Rsrc}
 
 {The Virus found alert and its sub-messages}
 kVirusAlrt =  1282; {A Virus has been detected!}
 kCountRsrcMissing = 1;   {The Resource count Resource is missing}
 kTypeMiscount   = 2;{Wrong number of resource types}
 kRsrcMiscount   = 3;{Wrong number of a specific res. kind}
 
 TYPE
 {Resource & Count list.}
 RsrcCount = RECORD
 RType: ResType;
 RCount:INTEGER;
 END;
 
 RsrcRSRC = ARRAY[0..0] OF RsrcCount;
 pRsrcRSRC = ^RsrcRSRC;
 hRsrcRSRC = ^pRsrcRSRC;
 
 VAR
 {For counting Resources.}
 theResType:ResType; { The kind we’re looking for }
 subMsgNo:INTEGER; { Submessage number }
 msgStr,{ Submessage to go into dialog}
 workStr: Str255;{ Resource name to go into the message }
 
 aRsrcRSRC: hRsrcRSRC;  { Handle to the Count Rsrc}
 
 i:INTEGER;
 dummy: INTEGER;
 
 LABEL 100;
BEGIN   { ApplicationCanRun }
 ApplicationCanRun := FALSE;{Assume failure.}
 
 {Virus Check: Load resources with counts of various kinds of resources
  in Application. Make sure the counts in the resource match the actual
  counts in Application.}
 workStr[0] := CHR(0);    {Make WorkStr have no length.}
 
 {Try to get the counts of the various resources in the Application.}
 aRsrcRSRC := hRsrcRSRC(Get1Resource(kVirusChkKinds, kVirusChkID));
 IF aRsrcRSRC <> NIL THEN BEGIN
 
 {Check out each of the counts read.}
 FOR i := 0 TO GetHandleSize(Handle(aRsrcRSRC)) div SIZEOF(RsrcCount) 
- 1 DO BEGIN
 
 {If the kind is a 0, a total resource count is wanted.}
 IF ORD(aRsrcRSRC^^[i].RType[1]) = 0 THEN BEGIN
 
 {Does the total number of resource kinds in the Application
  match the count the resource?}
 IF (Count1Types <> aRsrcRSRC^^[i].RCount) THEN BEGIN
 
 subMsgNo := kTypeMiscount; { Sub message }
 
 {Issue a Virus Alert to the user.}
100:    GetIndString(msgStr, kVirusAlrt, subMsgNo);
 ParamText(msgStr, workStr, '', '');
 dummy := StopAlert(kVirusAlrt, NIL);
 
 EXIT(ApplicationCanRun);
 END;
 END
 
 {Otherwise, check a specific type.}
 ELSE BEGIN
 
 {Does the number of this kind of resource in the Application
  match the count the resource?}
 theResType := aRsrcRSRC^^[i].RType;
 IF Count1Resources(theResType) <> aRsrcRSRC^^[i].RCount THEN BEGIN
 
 { Make a string out of the resource type. }
 WorkStr[0] := CHR(4);
 BlockMove(@theResType[1], @workStr[1], 4);
 
 subMsgNo := kRsrcMiscount; { Sub message }
 
 GOTO 100;
 END;
 END;
 END;   {End FOR i }
 
 {Finished with the resource}
 ReleaseResource(Handle(aRsrcRSRC));
 END    {End IF aRsrcRSRC <> NIL}
 
 {Count Resource not found.}
 ELSE BEGIN
 subMsgNo := kCountRsrcMissing;    { Sub message }
 
 GOTO 100;
 END;
 
 {Possibly put other virus checks, checks for the proper system version,
  etc. here.}
 
 ApplicationCanRun := TRUE; {Success!}
END;    { ApplicationCanRun }

END.
 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

Mac DVDRipper Pro 4.1.7 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
MYStuff Pro 2.0.16 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
TurboTax 2013.r17.002 - Manage your 2013...
TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more

Latest Forum Discussions

See All

Living Planet - Tiny Planet Videos and P...
Living Planet - Tiny Planet Videos and Photos 1.0 Device: iOS Universal Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: 50% OFF LAUNCH SPECIAL! BUY NOW BEFORE THE PRICE GOES UP... | Read more »
Livescribe 3 Smartpen Review
Made by: Livescribe Price: $149.99 for Livescribe 3 Hardware/iOS Integration Rating: 4.5 out of 5 stars Usability Rating: 4 out of 5 stars Reuse Value Rating: 4.75 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.44 out of... | Read more »
Unpossible Review
Unpossible Review By Carter Dotson on April 17th, 2014 Our Rating: :: RALPH WIGGUM APPROVESUniversal App - Designed for iPhone and iPad Unpossible is much better than its English!   | Read more »
Hitman GO Review
Hitman GO Review By Carter Dotson on April 17th, 2014 Our Rating: :: GO HITMAN, GO!Universal App - Designed for iPhone and iPad Hitman GO is not the obvious way to do a mobile version of the Hitman series, but it’s an incredibly... | Read more »
Monster High Ghouls and Jewels is a Frea...
Monster High Ghouls and Jewels is a Freaky Fashion-Forward Match-3 Puzzler Posted by Rob Rich on April 17th, 2014 [ permalink ] | Read more »
Dinosaur Train A to Z Review
Dinosaur Train A to Z Review By Amy Solomon on April 17th, 2014 Our Rating: :: DINO DETAILSUniversal App - Designed for iPhone and iPad Dinosaur Train A to Z is an educational app about dinosaurs that includes In-App Purchases... | Read more »
Easter Comes to Junk Jack X – Bringing N...
Easter Comes to Junk Jack X – Bringing New Crafts, Chemistry, and More Posted by Rob Rich on April 17th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Call of Cookie Review
Call of Cookie Review By Jordan Minor on April 17th, 2014 Our Rating: :: COOKIE CRUMBLESUniversal App - Designed for iPhone and iPad Call of Cookie proves that plants aren’t the only fighting foods out there.   | Read more »
Corel Launches Video Editing App Pinnacl...
Corel Launches Video Editing App Pinnacle Studio for iPhone, Updates iPad Version for iOS 7 Posted by Tre Lawrence on April 17th, 2014 [ | Read more »
Bad Vamp Review
Bad Vamp Review By Jennifer Allen on April 17th, 2014 Our Rating: :: BASIC VAMPIRIC ADVENTURESUniversal App - Designed for iPhone and iPad Run or destroy the vampires in this simple, single-screen game that lacks real bite.   | Read more »

Price Scanner via MacPrices.net

Apple restocks refurbished Mac minis starting...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more
Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more
Save up to $270 with Apple refurbished 13-inc...
The Apple Store has Apple Certified Refurbished October 2013 13″ Retina MacBook Pros available starting at $1099, with models up to $270 off MSRP. Apple’s one-year warranty is standard, and shipping... Read more
Apple now offering refurbished iPad mini with...
The Apple Store has Certified Refurbished 2nd generation iPad minis with Retina Displays now available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free.... Read more
Microsoft Blinks – Drops Microsoft Office 365...
Microsoft has dropped the annual subscription fee for Microsoft Office 365 Personal – which is needed in order to create and edit documents in Microsoft Office for iPad. However, Apple’s iOS and OS X... Read more
New AVG Vault Apps for iOS and Android Help K...
AVG Technologies N.V. an online security company for 177 million active users, has announced the launch of its latest mobile application, AVG Vault. The free app introduces an innovative user... Read more
Free Local Carrot iPhone App Helps Find Fresh...
I love fresh vegetables. I’m not a vegan, although I was for several years in the 1980s, but fresh vegetables and other whole foods are still my dietary mainstays as a matter of taste rather than... Read more
CarSO Pro – Car Service and Finance Manager/O...
Lviv, Ukraine-based BM-Studios’ CarSO Pro is a tool to manage operations concerning your car. Never forget to change the oil or prolong the insurance for your car. Remember when you’ve done the car... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Manager - Holyoke - Apple I...
Job Summary Keeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you’re a master of them all. In the store’s fast-paced, Read more
*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Market Leader - Cincinnati...
…challenges of developing individuals, building teams, and affecting growth across Apple Stores. You demonstrate successful leadership ability - focusing on excellence Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.