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.
 

Community Search:
MacTech Search:

Software Updates via MacUpdate

TinkerTool 5.4 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Tinderbox 6.3.1 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
Parallels Desktop 10.2.2 - Run Windows a...
Parallels Desktop is simply the world's bestselling, top-rated, and most trusted solution for running Windows applications on your Mac. With Parallels Desktop for Mac, you can seamlessly run both... Read more
Adobe Premiere Pro CC 2015 9.0.1 - Digit...
Premiere Pro CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Premiere Pro customer). Premiere Pro CS6 is still available for... Read more
Adobe After Effects CC 2015 13.5.1 - Cre...
After Effects CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous After Effects customer). After Effects CS6 is still available... Read more
Adobe Creative Cloud 2.2.0.129 - Access...
Adobe Creative Cloud costs $49.99/month (or less if you're a previous Creative Suite customer). Creative Suite 6 is still available for purchase (without a monthly plan) if you prefer. Introducing... Read more
Tower 2.2.3 - Version control with Git m...
Tower is a powerful Git client for OS X that makes using Git easy and more efficient. Users benefit from its elegant and comprehensive interface and a feature set that lets them enjoy the full power... Read more
Apple Java 2015-001 - For OS X 10.7, 10....
Apple Java for OS X 2015-001 installs the legacy Java 6 runtime for OS X 10.11 El Capitan, OS X 10.10 Yosemite, OS X 10.9 Mavericks, OS X 10.8 Mountain Lion, and OS X 10.7 Lion. This package is... Read more
Adobe Muse CC 2015 2015.0.1 - Design and...
Muse CC 2015 is available as part of Adobe Creative Cloud for as little as $14.99/month (or $9.99/month if you're a previous Muse customer). Muse CS6 is still available for purchase (without a... Read more
Adobe Illustrator CC 2015 19.1.0 - Profe...
Illustrator CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Illustrator customer). Illustrator CS6 is still available for... Read more

This Week at 148Apps: July 20-24, 2015
July is Heating Up With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out... | Read more »
Red Game Without A Great Name (Games)
Red Game Without A Great Name 1.0.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.3 (iTunes) Description: The mechanical bird is flying through an unfriendly, Steampunk world. Help it avoid obstacles and deadly... | Read more »
Warhammer: Arcane Magic (Games)
Warhammer: Arcane Magic 1.0.2 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.2 (iTunes) Description: Engage in epic battles and tactical gameplay that challenge both novice and veteran in Warhammer: Arcane Magic, a... | Read more »
Mazes of Karradash (Games)
Mazes of Karradash 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The city of Karradash is under attack: the monsters of the Shadow Realms are emerging from the depths.No adventurer is... | Read more »
Battle Golf is the Newest Game from the...
Wrassling was a pretty weird - and equally great - little wressling game. Now the developers, Folmer Kelly and Colin Lane, have turned their attention to a different sport: golfing. This is gonna be weird. [Read more] | Read more »
Qbert Rebooted has the App Store Going...
The weird little orange... whatever... is back, mostly thanks to that movie which shall remain nameless (you know the one). But anyway it's been "rebooted" and now you can play the fancy-looking Qbert Rebooted on iOS devices. [Read more] | Read more »
Giant Monsters Run Amok in The Sandbox...
So The Sandbox has just hit version number 1.99987 (seriously), and it's added a lot more stuff. Just like every other update, really. [Read more] | Read more »
Fish Pond Park (Games)
Fish Pond Park 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: Nurture an idyllic slice of tourist's heaven into the top nature spot of the nation, furnishing it with a variety of... | Read more »
Look after Baby Buddy on your Apple Watc...
Parigami Gold is the new premium version of the match three puzzler that includes Apple Watch support and all new content. You won't simply be sliding tiles around on your wrist, the Apple Watch companion app is an all new mini-game in itself. You'... | Read more »
Swallow all of your opponents as the big...
Eat all of the opposition and become the largest ball in Battle of Balls now available in the App Store and Google Play. Battle of Balls pits you against other opponents in real time and challenges you to eat more balls and grow larger than all of... | Read more »

Price Scanner via MacPrices.net

Sale! 13″ 1.6GHz/256GB MacBook Air for $1099,...
B&H Photo has the 13″ 1.6GHz/256GB MacBook Air on sale for $1099 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model. Read more
iPad mini 4 To Be Upgraded To iPad Air 2 Spec...
There’s a certain inevitability about making Apple product predictions this time of year. Come September, we can pretty reliably count on the release of refreshed iPhones, along with the iOS 9... Read more
Apple restocks refurbished Mac minis for up t...
The Apple Store has restocked Apple Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz... Read more
13-inch 2.5GHz MacBook Pro on sale for $899,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $899.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $200 off MSRP. Price is... Read more
21-inch 2.9GHz iMac on sale for $1299, save $...
Best Buy has the 21″ 2.9GHz iMac on sale today for $1299.99 on their online store. Choose free shipping or free local store pickup (if available). Their price is $200 off MSRP, and it’s the lowest... Read more
Free Image Sizer 1.3 for iOS Offers Photo Edi...
Xi’An, China based G-Power has announced the release of Image Sizer 1.3 for the iPhone, iPad, and iPod touch, an important update to their free photo editing app. Image Sizer’s collection of easy to... Read more
Sale! 13″ 1.6GHz/128GB MacBook Air for $899,...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model. Read more
13-inch Retina MacBook Pros on sale for $100...
Best Buy has 13-inch Retina MacBook Pros on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Prices are for online orders only, in-store... Read more
Will BMW’s i3 Electric Vehicle Be The Automo...
The German-language business journal Manager Magazin’s Michael Freitag reports that Apple and the German performance/luxury automaker Bayerishe Motoren Werke (BMW) are back at far-reaching... Read more
Sale! $250 off 15-inch Retina MacBook Pro, $2...
B&H Photo has lowered their price for the 15″ 2.2GHz Retina MacBook Pro to $1749, or $250 off MSRP. Shipping is free, and B&H charges NY sales tax only. They have the 27″ 3.3GHz 5K iMac on... Read more

Jobs Board

*Apple* Customer Experience (ACE) Leader - A...
…management to deliver on business objectives Training partner store staff on Apple products, services, and merchandising guidelines Coaching partner store staff on Read more
Project Manager - *Apple* Pay Security - Ap...
**Job Summary** The Apple Pay Security team is seeking a highly organized, results-driven Project Manager to drive the development of Apple Pay Security. If you are Read more
*Apple* TV Product Design Internship (Spring...
…the mechanical design effort associated with creating world-class products with the Apple TV PD Group. Responsibilities will include working closely with manufacturing, Read more
*Apple* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.