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

OmniGraffle 7.3 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
OmniGraffle Pro 7.3 - Create diagrams, f...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
DEVONthink Pro 2.9.11 - Knowledge base,...
DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research papers, your life often fills your hard drive in the... Read more
DiskCatalogMaker 6.8.1 - Catalog your di...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast Finder-like intuitive look and feel Super-fast search algorithm Can compress catalog data for... Read more
Tunnelblick 3.7.0 - GUI for OpenVPN.
Tunnelblick is a free, open source graphic user interface for OpenVPN on OS X. It provides easy control of OpenVPN client and/or server connections. It comes as a ready-to-use application with all... Read more
Adobe Dreamweaver CC 2017 17.0.2.9391 -...
Dreamweaver CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Dreamweaver customer). Adobe Dreamweaver CC 2017 allows you to... Read more
Adobe Animate CC 2017 16.2.0 - Advanced...
Animate CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Flash Professional customer). Animate CC 2017 (was Flash CC) lets you... Read more
A Better Finder Rename 10.15 - File, pho...
A Better Finder Rename is the most complete renaming solution available on the market today. That's why, since 1996, tens of thousands of hobbyists, professionals and businesses depend on A Better... Read more
Creative Kit 1.1 - $149.99
Creative Kit 2016--made exclusively for Mac users--is your ticket to the most amazing images you've ever created. With a variety of powerful tools at your fingertips, you'll not only repair and fine-... Read more
iMazing 2.2.3 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more

Power Rangers: Legacy Wars beginner...
Rita Repulsa is back, but this time she's invading your mobile phone in Power Rangers: Legacy Wars. What looks to be a straightforward beat 'em up is actually a tough-as-nails multiplayer strategy game that requires some deft tactical maneuvering.... | Read more »
Hearthstone celebrates the upcoming Jour...
Hearthstone gets a new expansion, Journey to Un'Goro, in a little over a week, and they'll be welcoming the Year of the Mammoth, the next season, at the same time. There's a lot to be excited about, so Blizzard is celebrating in kind. Players will... | Read more »
4 smart and stylish puzzle games like Ty...
TypeShift launched a little over a week ago, offering some puzzling new challenges for word nerds equipped with an iOS device. Created by Zach Gage, the mind behind Spelltower, TypeShift boasts, like its predecessor, a sleak design and some very... | Read more »
The best deals on the App Store this wee...
Deals, deals, deals. We're all about a good bargain here on 148Apps, and luckily this was another fine week in App Store discounts. There's a big board game sale happening right now, and a few fine indies are still discounted through the weekend.... | Read more »
The best new games we played this week
It's been quite the week, but now that all of that business is out of the way, it's time to hunker down with some of the excellent games that were released over the past few days. There's a fair few to help you relax in your down time or if you're... | Read more »
Orphan Black: The Game (Games)
Orphan Black: The Game 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Dive into a dark and twisted puzzle-adventure that retells the pivotal events of Orphan Black. | Read more »
The Elder Scrolls: Legends is now availa...
| Read more »
Ticket to Earth beginner's guide: H...
Robot Circus launched Ticket to Earth as part of the App Store's indie games event last week. If you're not quite digging the space operatics Mass Effect: Andromeda is serving up, you'll be pleased to know that there's a surprising alternative on... | Read more »
Leap to victory in Nexx Studios new plat...
You’re always a hop, skip, and a jump away from a fiery death in Temple Jump, a new platformer-cum-endless runner from Nexx Studio. It’s out now on both iOS and Android if you’re an adventurer seeking treasure in a crumbling, pixel-laden temple. | Read more »
Failbetter Games details changes coming...
Sunless Sea, Failbetter Games' dark and gloomy sea explorer, sets sail for the iPad tomorrow. Ahead of the game's launch, Failbetter took to Twitter to discuss what will be different in the mobile version of the game. Many of the changes make... | Read more »

Price Scanner via MacPrices.net

Is Apple Planning An iPhone Based Modular Doc...
Today’s more powerful and larger-screened smartphones and phablets are becoming the default anchor computing device for more and more users computing devices, but even a five or six inch panel is not... Read more
Razer Launches New Razer Blade Pro World’s Fi...
Razer, the gaming and high performance hardware specialists, have announced the new Razer Blade Pro laptop — the first laptop to be qualified for THX Mobile Certification, an accreditation reserved... Read more
Gro CRM’s Apple Small Business Mac And iOS CR...
Gro Software, developers of the Mac CRM software for small business and enterprise, are included in FinancesOnline 2017 CRM Rising Stars and Great User Experience lists by business software review... Read more
Deal alert! 15-inch and 13-inch MacBook Pros...
B&H Photo has the new 2016 15″ and 13″ Apple MacBook Pros in stock today and on sale for up to $200 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
Save up to $420 on a new MacBook Pro with App...
Apple is offering Certified Refurbished 2016 15″ and 13″ MacBook Pros, including some Touch Bar models, for up to $420 off original MSRP. An Apple one-year warranty is included with each model, and... Read more
12-inch 1.2GHz Retina MacBooks on sale for $1...
B&H has 12″ 1.2GHz Retina MacBooks on sale for up to $200 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 12″ 1.2GHz Space Gray Retina MacBook: $1449 $150 off MSRP - 12″ 1.... Read more
Is A New 10.5-inch iPad Still Coming In April...
There was no sign or mention of a long-rumored and much anticipated 10.5-inch iPad Pro in Apple’s product announcements last week. The exciting iPad news was release of an upgraded iPad Air with a... Read more
T-Mobile’s Premium Device Protection Now Incl...
Good news for T-Mobile customers who love their iPhones and iPads. The “Un-carrier” has become the first national wireless company to give customers AppleCare Services at zero additional cost as part... Read more
FileWave Ensures Support for Latest Apple OS...
FileWave multi-platform device management providers announced support for Apple’s release yesterday of iOS 10.3, macOS Sierra 10.12.4, and tvOS 11.2. FileWave has a history of providing zero-day... Read more
Use Apple’s Education discount to save up to...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free: -... Read more

Jobs Board

Fulltime aan de slag als shopmanager in een h...
Ben jij helemaal gek van Apple -producten en vind je het helemaal super om fulltime shopmanager te zijn in een jonge en hippe elektronicazaak? Wil jij werken in Read more
Desktop Analyst - *Apple* Products - Montef...
…technology to improve patient care. JOB RESPONSIBILITIES: Provide day-to-day support for Apple Hardware and Software in the environment based on the team's support Read more
*Apple* Mobile Master - Best Buy (United Sta...
**493168BR** **Job Title:** Apple Mobile Master **Location Number:** 000827-Denton-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** At Read more
Fulltime aan de slag als shopmanager in een h...
Ben jij helemaal gek van Apple -producten en vind je het helemaal super om fulltime shopmanager te zijn in een jonge en hippe elektronicazaak? Wil jij werken in Read more
*Apple* Mobile Master - Best Buy (United Sta...
**492889BR** **Job Title:** Apple Mobile Master **Location Number:** 000886-Norwalk-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.