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
$105.22
Apple Inc.
+0.39
MSFT
$46.13
Microsoft Corpora
+1.11
GOOG
$539.78
Google Inc.
-4.20

MacTech Search:
Community Search:

Software Updates via MacUpdate

OS X Server 4.0 - For OS X 10.10 Yosemit...
Designed for OS X and iOS devices, OS X Server makes it easy to share files, schedule meetings, synchronize contacts, develop software, host your own website, publish wikis, configure Mac, iPhone,... Read more
TotalFinder 1.6.12 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Tab-based... Read more
BusyCal 2.6.3 - Powerful calendar app wi...
BusyCal is an award-winning desktop calendar that combines personal productivity features for individuals with powerful calendar sharing capabilities for families and workgroups. BusyCal's unique... Read more
calibre 2.7 - Complete e-library managem...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
Skitch 2.7.3 - Take screenshots, annotat...
With Skitch, taking, annotating, and sharing screenshots or images is as fun as it is simple.Communicate and collaborate with images using Skitch and its intuitive, engaging drawing and annotating... Read more
Delicious Library 3.3.2 - Import, browse...
Delicious Library allows you to import, browse, and share all your books, movies, music, and video games with Delicious Library. Run your very own library from your home or office using our... Read more
Art Text 2.4.8 - Create high quality hea...
Art Text is an OS X application for creating high quality textual graphics, headings, logos, icons, Web site elements, and buttons. Thanks to multi-layer support, creating complex graphics is no... Read more
Live Interior 3D Pro 2.9.6 - Powerful an...
Live Interior 3D Pro is a powerful yet very intuitive interior designing application. View Video Tutorials It has every feature of Live Interior 3D Standard, plus some exclusive ones: Create multi... Read more
The Hit List 1.1.7 - Advanced reminder a...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
jAlbum Pro 12.2.4 - Organize your digita...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more

Latest Forum Discussions

See All

Rami Ismail Opens Up distribute​() for D...
Rami Ismail Opens Up distribute​() for Developers Posted by Jessica Fisher on October 24th, 2014 [ permalink ] Rami Ismail, Chief Executive of Business and Development at indie game studio | Read more »
Great Hitman GO Goes on Sale and Gets Ne...
Great Hitman GO Goes on Sale and Gets New Update – Say That Three Times Fast Posted by Jessica Fisher on October 24th, 2014 [ permalink ] | Read more »
Rival Stars Basketball Review
Rival Stars Basketball Review By Jennifer Allen on October 24th, 2014 Our Rating: :: RESTRICTIVE BUT FUNUniversal App - Designed for iPhone and iPad Rival Stars Basketball is a fun mixture of basketball and card collecting but its... | Read more »
Rubicon Development Makes Over a Dozen o...
Rubicon Development Makes Over a Dozen of Their Games Free For This Weekend Only Posted by Jessica Fisher on October 24th, 2014 [ permalink ] | Read more »
I Am Dolphin Review
I Am Dolphin Review By Jennifer Allen on October 24th, 2014 Our Rating: :: NEARLY FIN-TASTICUniversal App - Designed for iPhone and iPad Swim around and eat nearly everything that moves in I Am Dolphin, a fun Ecco-ish kind of game... | Read more »
nPlayer looks to be the ultimate choice...
Developed by Newin Inc, nPlayer may seem like your standard video player – but is aiming to be the best in its field by providing high quality video play performance and support for a huge number of video formats and codecs. User reviews include... | Read more »
Fighting Fantasy: Caverns of the Snow Wi...
Fighting Fantasy: Caverns of the Snow Witch Review By Jennifer Allen on October 24th, 2014 Our Rating: :: CLASSY STORYTELLINGUniversal App - Designed for iPhone and iPad Fighting Fantasy: Caverns of the Snow Witch is a sterling... | Read more »
A Few Days Left (Games)
A Few Days Left 1.01 Device: iOS Universal Category: Games Price: $3.99, Version: 1.01 (iTunes) Description: Screenshots are in compliance to App Store's 4+ age rating! Please see App Preview for real game play! **Important: Make... | Read more »
Toca Boo (Education)
Toca Boo 1.0.2 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0.2 (iTunes) Description: BOO! Did I scare you!? My name is Bonnie and my family loves to spook! Do you want to scare them back? Follow me and I'll... | Read more »
Intuon (Games)
Intuon 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Join the battle with your intuition in a new hardcore game Intuon! How well do you trust your intuition? Can you find a needle in a... | Read more »

Price Scanner via MacPrices.net

Weekend sale: 13-inch 128GB MacBook Air for $...
Best Buy has the 2014 13-inch 1.4GHz 128GB MacBook Air on sale for $849.99, or $150 off MSRP, on their online store. Choose free home shipping or free local store pickup (if available). Price valid... Read more
Nimbus Note Cross=Platform Notes Utility
Nimbus Note will make sure you never forget or lose your valuable data again. Create and edit notes, save web pages, screenshots and any other type of data – and share it all with your friends and... Read more
NewerTech’s Snuglet Makes MagSafe 2 Power Con...
NewerTech has introduced the Snuglet, a precision-manufactured ring designed to sit inside your MagSafe 2 connector port, providing a more snug fit to prevent your power cable from unintentional... Read more
Apple Planning To Sacrifice Gross Margins To...
Digitimes Research’s Jim Hsiao says its analysts believe Apple is planning to sacrifice its gross margins to save its tablet business, which has recently fallen into decline. They project that Apple’... Read more
Who’s On Now? – First Instant-Connect Search...
It’s nighttime and your car has broken down on the side of the highway. You need a tow truck right away, so you open an app on your iPhone, search for the closest tow truck and send an instant... Read more
13-inch 2.5GHz MacBook Pro on sale for $949,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $949.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $150 off MSRP. Price is... Read more
Save up to $125 on Retina MacBook Pros
B&H Photo has the new 2014 13″ and 15″ Retina MacBook Pros on sale for up to $125 off MSRP. Shipping is free, and B&H charges NY sales tax only. They’ll also include free copies of Parallels... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
Textilus New Word, Notes and PDF Processor fo...
Textilus is new word-crunching, notes, and PDF processor designed exclusively for the iPad. I haven’t had time to thoroughly check it out yet, but it looks great and early reviews are positive.... Read more
WD My Passport Pro Bus-Powered Thunderbolt RA...
WD’s My Passport Pro RAID solution is powered by an integrated Thunderbolt cable for true portability and speeds as high as 233 MB/s. HighlightsOverviewSpecifications Transfer, Back Up And Edit In... Read more

Jobs Board

*Apple* Solutions Consultant - Apple Inc. (U...
…important role that the ASC serves is that of providing an excellent Apple Customer Experience. Responsibilities include: * Promoting Apple products and solutions Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, 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
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.