TweetFollow Us on Twitter

Volume Number:4
Issue Number:5
Column Tag:Advanced Mac'ing

A Vaccine for the 'nVIR' Virus

By Mike™ Scanlin, Contributing Editor

Unless you are going to Africa or Indochina, viruses and vaccinations are not something that most of us need to worry about. However, even if you’re not planning on travelling, there is one virus you need to be aware of. It is a computer virus that is infecting Macintoshes everywhere. [Note: The virus described in this article is apparently only one of at least three viruses that are going around as reported in the press. This article discusses what we shall name the ‘nVIR’ virus. The other two are the infamous ‘peace message’ virus and the ‘scrapbook’ virus reported in this month’s mousehole column, and in a recent MacWeek article. -Ed]

Are you infected?

Use ResEdit to open your system file and look for ‘nVIR’ resources. If you have them, then your system has been infected and chances are that at least some (if not most or all) of your applications are infected. Don’t panic. This particular virus is relatively harmless. There is an application at the end of this article that will allow you to remove the virus from your infected applications. There is also an ‘INIT’ resource you can put in your System Folder that will warn you if this virus ever shows up on your system. [Note that this vaccine and virus warning init applies only to this particular ‘nVIR’ virus. New vaccines will be necessary for the other two once it is known how they operate. -Ed]

Fig. 1 Vaccination Alert tells Application status

How I found it

Until last week, I had had no experience with computer viruses. I had heard rumors about the existence of Mac viruses, but didn’t really believe them. I do not know when this virus first got into my system. It must have come from some program I downloaded off of a network, but I do not know which one. By the time I figured out what was going on, the virus had modified seventeen of the applications on my hard disk and my System file.

Virus Symptoms

Sometime near the beginning of last week, I started hearing a beep when launching programs. It didn’t happen every time, only once in a while and with no discernable pattern. Using TMON, I trapped SysBeep() and discovered that something was modifying ‘CODE’ 0 and installing several ‘nVIR’ resources into every application I launched. I looked in my System file and, in addition to several ‘nVIR’ resources, found an ‘INIT’ 32 resource that I didn’t put there. I compared the standard ‘INIT’s from an original system disk and none of them matched the ‘INIT’ 32 I had found. What really clued me in to the idea of a virus was that if I took the ‘INIT’ 32 resource out of my System file, quit ResEdit, and then relaunched ResEdit, the ‘INIT’ 32 resource would be back in there. After disassembling ‘INIT’ 32, I learned how it worked and how to make my system immune to it. I am sharing this information so that other Mac users can protect themselves as well. [Note that this virus exhibits the ability to re-install itself after being patched out with ResEdit! -Ed]

How to make your System file immune

Use ResEdit to open your System file. Create an ‘INIT’ 32 resource that consists of these 2 hex bytes: 4E 75 (which is an RTS instruction). If ‘INIT’ 32 already exists and has a size of 366 bytes, then you can be pretty sure it is the virus’ ‘INIT’. Replace the existing ‘INIT’ 32 with the 2 byte version (4E 75). Now create 8 resources of the type ‘nVIR’; the case of the resource type is important -- do not use ‘NVIR’ or ‘nvir’. Their IDs should be 0 through 7, with size zero bytes. If they already exist, then delete them and create 8 new empty ones (with IDs 0-7).

That’s it. Your system is now immune to this particular virus (but not all possible viruses). If you now run an infected application, the virus will think that it is already installed in your system file, since it sees the ‘INIT’ and ‘nVIR’ resources it expects, and will leave it alone.

If your System file was infected before you immunized it, you should reboot the system before using the procedure below to remove the virus from your applications. This guarantees that the effects of ‘INIT’ 32 are removed from memory.

Removing the virus from infected applications

If an application has been infected, it will have several ‘nVIR’ resources, a ‘CODE’ 256 resource, and a possibly modified ‘CODE’ 0 resource. Here are instructions on how to restore an infected application (note: this is only useful if you are certain that your System file is not infected. Otherwise, the applications will become infected again. Also, you should practice on a copy of an infected application):

1) Open the application with ResEdit. If ‘CODE’ 256 exists, use GetInfo on it to check its size. If it is 372 bytes, then remove it. The reason we check for the size is because some applications, such as ReadySetGo, already have a ‘CODE’ 256 resource of their own and we don’t want to remove part of the application’s code.

2) Open ‘CODE’ 0 and look at the 3rd line of 8 hex bytes (bytes 16-23). If it is “0000 3F3C 0100 A9F0” then you need to replace that line of hex numbers with the 8 bytes contained in the ‘nVIR’ 2 resource. If the third line does not look like the above 8 bytes, then the ‘CODE’ resource is probably protected and did not get modified -- see below for an explanation. In this case leave it alone.

3) Remove all ‘nVIR’ resources. Make sure you have completed step 2 before removing ‘nVIR’ 2. You cannot restore the application without it.

Because this procedure is so automatic, I have written a program that does it for you. The application Vaccination displays the SFGetFile dialog and allows you to choose an application to vaccinate. A message is displayed that tells you the result of the vaccination and the SFGetFile dialog is displayed again. If your system has been infected, you should vaccinate every application on your hard drive. You will only see files of type ‘APPL’, ‘FNDR’ (for the Finder), and ‘dahd’ (for the DA handler) in the SFGetFile dialog so you might want to do a manual tree walk of your hard drive to be sure you vaccinate all of your applications. There is no harm in vaccinating an uninfected application or in vaccinating the same application more than once. This program does not make applications immune to this virus, it only removes this virus from them. But if your System file is immune, then there is no way this particular virus can spread to your applications. Note: you cannot use the Vaccination program to make your System file immune. You will have to do that manually using the procedure above.

How this virus works

This particular virus modifies the ‘CODE’ 0 resource of an application in such a way that when you launch that application the first thing to execute is a piece of virus installation code. That installation code looks for the virus’ presence in the System file you are launching from. If it does not find evidence of the virus, it then installs itself (as ‘INIT’ 32 and several ‘nVIR’ resources) into your System file and then executes the application you had originally launched. Once your System file is infected, every application launched from that system will become infected. The whole infection process only takes a second or two, so there is little chance you will notice it. If the virus detects that it is already in the System file and in the application you are launching (meaning that no installation of itself is necessary on this launch), then there is about a 6% chance (1 in 16) that you will hear a short beep. This is the beep that first got my attention. According to a friend of mine, Chris Borton, whose computer was also infected, if you have MacinTalk in your System Folder, then the virus speaks the words “Don’t Panic” instead of beeping.

This virus does not check if the ‘CODE’ 0 resource of the application it is trying to infect is protected or not. Consequently, applications that have ‘CODE’ 0 resources with the resProtected bit set are still infected, but are not contagious, i.e. they have the ‘CODE’ 256 resource and the ‘nVIR’ resources added to them, but they can not pass the virus on to a clean System file. I learned this by noticing that QUED/M and PageMaker were infected, but were not contagious. I couldn’t figure out why some programs had protected ‘CODE’ resources and others didn’t. Then one of the people I work with, Victor Romano, put it together. He told me that Lightspeed C (which QUED/M and PageMaker were written in) automatically sets the resProtected bit of the ‘CODE’ resources it generates. MPW does not. So, protecting the ‘CODE’ resources (which can be done with ResEdit) is another simple way of preventing this virus from affecting an application.

To be forewarned

I don’t know how far this virus has already spread, or how far it will spread. As a partial defense, however, I have written a piece of code that can be installed as an ‘INIT’ file in your System Folder that will warn you if it detects something that looks like this particular virus. VirusWarnINIT is a patch on 2 routines that this virus relies on: GetResource() and ChangedResource(). The patch to GetResource() makes a beep if theType == ‘nVIR’. The patch to ChangedResource() makes a beep if theResource is a handle to a ‘CODE’ 0 resource. I wouldn’t suggest installing this ‘INIT’ in a system known to be infected -- the number of beeps is sure to annoy you. I would have used something like an alert window instead of a beep as a warning, but I can’t be sure that the Window Manager has been initialized at the time the virus is detected. If you install this ‘INIT’ in a clean system and then launch a contagious application, you will hear about 5 or 6 beeps in a row as the virus tries to install itself in your System file.

Note that this ‘INIT’ is only a warning, not a vaccination. The virus will still install itself. The advantage is that you will know about it right away and can stop it before it spreads very far.

Now that my Mac has been vaccinated, it’s my turn. After Typhoid, Yellow Fever, Cholera and Meningococcal vaccinations, I’m off to Africa and Indochina. I wonder if I can get David Smith to send MacTutor to Serengeti National Park? Or do they already get it there? I’ll let you know

/* Vaccination.c
   * by Mike™ Scanlin   12 March 88
   * Removes the ‘nVIR’ virus from an 
 * application chosen by the user.

#define NIL 0L
#define reg register


#define nVIR_CODE_256_SIZE372

#define nVIR2Bad -10
#define nVIR2NotFound-11

void    RemoveResourceFromFile(long theType, int theID, int    
intInnoculate(Str255 *fileName, int vRef);
void    pStrCpy(char *p2, char *p1);
Boolean ChooseFile(Str255 *fn, int *vRef);
void    main(void);

static  SFReply  reply;
static  int applResFile;

/* RemoveResourceFromFile(theType, theID, refNum)
   * This will remove the resource of type theType 
 * and ID theID from the open resource file
   * whose refNum is refNum.
void  RemoveResourceFromFile(theType, theID, refNum)
long  theType;
 reg Handle theResource;
 if ((theResource = GetResource(theType, theID)) && (HomeResFile(theResource) 
== refNum))

/* Innoculate(fileName, vRef)
  * This removes the ‘nVIR’ virus from *fileName 
 in directory vRef.
int     Innoculate(fileName, vRef)
reg Str255*fileName;
 reg Handle oldCODE, currentCODE;
 reg inti, refNum, returnVal;
 ParamBlockRec   pb;
 /* init the ParamBlockRec to all zeros */
 asm {
 lea    pb,A0
 move.l #sizeof(ParamBlockRec),D0
 subq.l #1,D0
 dbra D0,@1
 /* set the current working directory */
 pb.ioParam.ioVRefNum = vRef;
 PBHSetVol(&pb, FALSE);
 refNum = OpenResFile(fileName);
 if ((oldCODE = GetResource(‘nVIR’, 2)) && (HomeResFile(oldCODE) == refNum)) 
 if (GetHandleSize(oldCODE) != 8)
 /* if ‘nVIR’ 2 isn’t 8 bytes, then something 
 isn’t right. */
 returnVal = nVIR2Bad;
 else {
 if ((currentCODE = GetResource(‘CODE’, 0)) && (HomeResFile(currentCODE) 
== refNum)) {
 asm {
 MOVE.L (A1),A1
 MOVE.L currentCODE, A0
 MOVE.L (A0),A0
 ADDA #16, A0
 MOVE.L (A1)+, (A0)+
 MOVE.L (A1), (A0)
 /* kill the ‘nVIR’ resources */
 for (i = 0; i <= 7; i++)
 RemoveResourceFromFile(‘nVIR’, i, refNum);

 /* kill the extra ‘CODE’ resource that this 
 virus adds (only if it has the size 
 of nVIR_CODE_256_SIZE) */
 if ((currentCODE = GetResource(‘CODE’, 256)) &&
 (GetHandleSize(currentCODE) == 
 nVIR_CODE_256_SIZE) && (HomeResFile(currentCODE) 
 == refNum))
 returnVal = noErr;
 returnVal = nVIR2NotFound;
 if (refNum != applResFile)

/* pStrCpy(p2, p1)
  * Copy the pascal string at *p1 to *p2.
void pStrCpy(p2, p1)
reg char*p2, *p1;
 reg intlen;
 len = *p2++ = *p1++;
 while (--len >= 0) 
 *p2++ = *p1++;

/* ChooseFile(fn, vRef)
   * Use SFGetFile() to get the name of an 
 * application from the user. Return the directory
   * of the chosen file in *vRef. Return FALSE if the 
 * user clicked Cancel, TRUE if they clicked
   * Open.
  * Thanks to Chris Borton for this routine.
Boolean ChooseFile(fn, vRef)
Str255  *fn;
 SFTypeList myTypes;
 static Point  SFGwhere = { 90, 82 };
 myTypes[0] = ‘APPL’;
 myTypes[1] = ‘FNDR’;
 myTypes[2] = ‘dahd’;
 SFGetFile(SFGwhere, NIL, 0L, 3, myTypes, 0L, &reply);
 if (reply.good) {
 pStrCpy((char *)fn , (char *)reply.fName);
 *vRef = reply.vRefNum;

void main() {
 Str255 fileName;
 int    vRef;
 /* save the application’s resource file refNum */
 applResFile = CurMap;

 /* keep choosing files until the user hits Cancel */
 while (ChooseFile(&fileName, &vRef)) {
 switch (Innoculate(&fileName, vRef)) {
 case   nVIR2Bad:
 ParamText(&fileName, “\pResource ‘nVIR’ 2 is not 8 bytes long. File 
cannot be repaired.”, NIL, NIL);
 case nVIR2NotFound:
 ParamText(&fileName, “\pResource ‘nVIR’ 2 not found. File is not infected 
or cannot be repaired.”, NIL, NIL);
 ParamText(&fileName, “\pVirus successfully removed.”, NIL, NIL);
 /* show the result of the attempted removal */

/* VirusWarnINIT.c
   * by Mike™ Scanlin   13 March 88
   * Put this in your system folder to warn you 
 * about the ‘nVIR’ virus.
   * It patches GetResource() and ChangedResource().
#include “Asm.h”
#include “ResourceMgr.h”

#define GetResource0xA9A0
#define ChangedResource 0xA9AA
#define JMP 0x4EF9
#define memFullErr -108
#define beepDuration 20

void  main(void);

void  main()
 asm  {

/* beginning of the code that installs the patches */

 move.l D3,-(SP)
/* get the original GetResource address */   
 move #GetResource,D0
/* set up the JMP instruction that calls the original GetResource */
 lea    @origGR,A1
 move #JMP,(A1)+
 move.l A0,(A1)

/* get the original ChangedResouce address */
 move #ChangedResource,D0
/* set up the JMP instruction that calls the original ChangedResource 
 lea    @origCR,A1
 move #JMP,(A1)+
 move.l A0,(A1)

/* get some space in the system heap for the patches */
 lea    @last,A0
 lea    @first,A1
 suba.l A1,A0    /* the length of our patches */
 move.l A0,D0
 add.l  #254,D0  /* the extra space for the Str255 at the end (@name) 
 move.l D0,D3    /* save for _BlockMove */
 cmpi   #memFullErr,D0
 beq.s  @noPatch
 move.l A0,-(SP) /* save for _BlockMove */
 move.l (SP),-(SP) /* for _SetTrapAddress */

/* set GetResource to the beginning of the space we just got in the system 
heap */
 move #GetResource,D0

/* set ChangedResource trap */
 lea    @changedResouce,A0
 lea    @getResource,A1
 suba.l A1,A0
 adda.l (SP)+,A0
 move #ChangedResource,D0
/* now move it into place */
 lea    @first,A0
 move.l (SP)+,A1
 move.l D3,D0

@noPatchmove.l (SP)+,D3
/* end of the code that installs the patches */


  * This is the patch to GetResource
 move.l 6(SP),D0 /* get theType */
 cmpi.l #’nVIR’,D0
 bne.s  @origGR

/* at this point we know something is trying to load an ‘nVIR’ resource 
 move #beepDuration,-(SP)
/* note that this is only a warning beep, it falls through 
 * to the original GetResource, so the calling function 
 * never knows that it was detected. */
@origGR nop /* JMP to original trap */

  * This is the patch to ChangedResource

/* call GetResInfo() to see if we are changing a CODE 0 resource */
 move.l 4(SP),-(SP)/* copy the resource handle 
 * that was passed to
   * ChangedResouce() */
 pea    @theID
 pea    @theType
 pea    @name
 lea    @theType,A0
 move.l (A0),D0
 cmpi.l #’CODE’,D0
 bne.s  @origCR
 lea    @theID,A0
 tst    (A0)
 bne.s  @origCR

/* give a warning beep a CODE 0 resource is being changed */   
 move #beepDuration,-(SP)
@origCR nop /* JMP to original trap */
@theID  dc0
@name   dc0 
 /* there are actually 254 more bytes to this
 * variable (for a total of 256). Check the
 * add.l #254,D0 instruction in the install code. */

Apple Inc.
Microsoft Corpora
Google Inc.

MacTech Search:
Community Search:

Software Updates via MacUpdate

Path Finder 6.5.5 - Powerful, award-winn...
Path Finder is a file browser that combines the familiar Finder interface with the powerful utilities and innovative features. Just a small selection of the Path Finder 6 feature set: Dual pane... Read more
QuarkXPress 10.2.1 - Desktop publishing...
With QuarkXPress, you can communicate in all the ways you need to -- and always look professional -- in print and digital media, all in a single tool. Features include: Easy to Use -- QuarkXPress is... Read more
Skype - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
VueScan 9.4.41 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Cloud 3.0.0 - File sharing from your men...
Cloud is simple file sharing for the Mac. Drag a file from your Mac to the CloudApp icon in the menubar and we take care of the rest. A link to the file will automatically be copied to your clipboard... Read more
LibreOffice - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
SlingPlayer Plugin - Browser...
SlingPlayer is the screen interface software that works hand-in-hand with the hardware inside the Slingbox to make your TV viewing experience just like that at home. It features an array of... Read more
Get Lyrical 3.8 - Auto-magically adds ly...
Get Lyrical auto-magically add lyrics to songs in iTunes. You can choose either a selection of tracks, or the current track. Or turn on "Active Tagging" to get lyrics for songs as you play them.... Read more
Viber 4.2.2 - Send messages and make cal...
Viber lets you send free messages and make free calls to other Viber users, on any device and network, in any country! Viber syncs your contacts, messages and call history with your mobile device,... Read more
Cocktail 7.6 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more

Latest Forum Discussions

See All

Rhonna Designs Magic (Photography)
Rhonna Designs Magic 1.0 Device: iOS Universal Category: Photography Price: $1.99, Version: 1.0 (iTunes) Description: Want to sprinkle *magic* on your photos? With RD Magic, you can add colors, filters, light leaks, bokeh, edges,... | Read more »
This Week at 148Apps: August 25-29, 2014
Shiny Happy App Reviews   | Read more »
Qube Kingdom – Tips, Tricks, Strategies,...
Qube Kingdom is a tower defense game from DeNA. You rally your troops – magicians, archers, knights, barbarians, and others – and fight against an evil menace looking to dominate your kingdom of tiny squares. Planning a war isn’t easy, so here are a... | Read more »
Qube Kingdom Review
Qube Kingdom Review By Nadia Oxford on August 29th, 2014 Our Rating: :: KIND OF A SQUARE KINGDOMUniversal App - Designed for iPhone and iPad Qube Kingdom has cute visuals, but it’s a pretty basic tower defense game at heart.   | Read more »
Fire in the Hole Review
Fire in the Hole Review By Rob Thomas on August 29th, 2014 Our Rating: :: WALK THE PLANKUniversal App - Designed for iPhone and iPad Seafoam’s Fire in the Hole looks like a bright, 8-bit throwback, but there’s not enough booty to... | Read more »
Alien Creeps TD is Now Available Worldwi...
Alien Creeps TD is Now Available Worldwide Posted by Ellis Spice on August 29th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Dodo Master Review
Dodo Master Review By Jordan Minor on August 29th, 2014 Our Rating: :: NEST EGGiPad Only App - Designed for the iPad Dodo Master is tough but fair, and that’s what makes it a joy to play.   | Read more »
Motorsport Manager Review
Motorsport Manager Review By Lee Hamlet on August 29th, 2014 Our Rating: :: MARVELOUS MANAGEMENTUniversal App - Designed for iPhone and iPad Despite its depth and sense of tactical freedom, Motorsport Manager is one of the most... | Read more »
Motorsport Manager – Beginner Tips, Tric...
The world of Motorsport management can be an unforgiving and merciless one, so to help with some of the stress that comes with running a successful race team, here are a few hints and tips to leave your opponents in the dust. | Read more »
CalPal Update Brings the App to 2.0, Add...
CalPal Update Brings the App to 2.0, Adds Lots of New Stuff Posted by Ellis Spice on August 29th, 2014 [ permalink ] | Read more »

Price Scanner via

Are We Now In The Post-Post-PC Era?
A longtime and thoroughgoing laptop aficionado, I was more than a little dismayed by Steve Jobs’s declaration back in 2010 when he sprang the iPad on an unsuspecting world. that we’d entered a “post-... Read more
Apple now offering refurbished 21-inch 1.4GHz...
The Apple Store is now offering Apple Certified Refurbished 21″ 1.4GHz iMacs for $929 including free shipping plus Apple’s standard one-year warranty. Their price is $170 off the cost of new models,... Read more
Save $50 on the 2.5GHz Mac mini, on sale for...
B&H Photo has the 2.5GHz Mac mini on sale for $549.99 including free shipping. That’s $50 off MSRP, and B&H will also include a free copy of Parallels Desktop software. NY sales tax only. Read more
Save up to $300 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $300 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
The Rise of Phablets
Carlisle & Gallagher Consulting Group, a businesses and technology consulting firm focused solely on the financial services industry, has released an infographic depicting the convergence of... Read more
Bad Driver Database App Allows Good Drivers t...
Bad Driver Database 1.4 by Facile Group is a new iOS and Android app that lets users instantly input and see how many times a careless, reckless or just plain stupid driver has been added to the... Read more
Eddy – Cloud Music Player for iPhone/iPad Fre...
Ukraine based CapableBits announces the release of Eddy, its tiny, but smart and powerful cloud music player for iPhone and iPad that allows users to stream or download music directly from cloud... Read more
A&D Medical Launches Its WellnessConnecte...
For consumers and the healthcare providers and loved ones who care for them, A&D Medical, a leader in connected health and biometric measurement devices and services, has launched its... Read more
Anand Lal Shimpi Retires From AnandTech
Anand Lal Shimpi, whose AnandTech Website is famous for its meticulously detailed and thoroughgoing reviews and analysis, is packing it in. Lal Shimpi, who founded the tech site at age 14 in 1997,... Read more
2.5GHz Mac mini, Apple refurbished, in stock...
The Apple Store has Apple Certified Refurbished 2.5GHz Mac minis available for $509, $90 off MSRP. Apple’s one-year warranty is included, and shipping is free. Read more

Jobs Board

*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
*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
*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
*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
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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.