Introduction to the antivirus protection - Which extensions are (un)safe

Probably each of us knows (or at least guesses) what is the use of extensions EXE, ZIP, DOC, JPG etc. There are more extensions in the computer - on the following lines you can meet at least the basic ones that are important for the computer security and antivirus protection.

Operating system DOS:

Extension Description Note
APP Digital Research DR-DOS executable DOS executables (16 bit)
BIN Device driver/binary image DOS executables (16 bit)
BO? Boot sector image Compressed executable boot images
COM Executable program file DOS executables (16 bit)
COM DIET, PKLITE, CRYPTCOM, ICE etc. Compressed executable files
DEV Device driver DOS executables (16 bit)
DRV Device driver DOS executables (16 bit)
EXE DIET, PKLITE, LZEXE, UPX etc. Compressed executable files
EXE Executable program DOS executables (16 bit)
EXE Self-extracting archives File archives
IM? Disk image Archive
MB* MBR image System
OV? Overlay DOS executables (16 bit)
SYS Device driver DOS executables (16 bit)
TD0 Deledisk diskette images Compressed boot images
00? Xtree overlays DOS executables (16 bit)

Operating system Windows:

Extension Description Note
ACM Audio Compression Module add-on Windows System file
CMD Windows NT batch file Windows 32-bit Executables
CPL Control Panel extension Windows 16-bit Executables
DEV Device driver Windows 32-bit Executables
DLL Dynamic Link Library Windows 16-bit Executables
DL? Dynamic Link Library Windows 32-bit Executables
DRV Device driver Windows 32-bit Executables
EXE DIET, PKLITE, LZEXE, UPX etc. Compressed Executable files
EXE New Executable Windows 16-bit Executables
EXE Portable Executable Windows 32-bit Executables
HLP Help files Windows 16-bit Executables
LNK Shortcut file Windows Executable
MOD Kernel Module Windows 16-bit Executables
MSC Microsoft Common Console Document
MSI MS Windows Installer File File archives
MSP Windows Installer Patch
PCI Windows PCI Miniport system file Windows Executables
PIF Program Information File Windows Executables
REG Windows Registry files
SCR Screen saver Windows 16-bit Executables
SYS Win NT device driver Windows 32-bit Executables
TSP Windows Telephony Service Windows Executables
VXD Virtual Device Drivers Windows 32-bit executables
VWP Audio plug-in Windows Executables
WIN Window file Windows 32-bit executables
?? MS Compress/Expand Compressed executable files
286 Device driver for Windows 2.0 and 3.x real mode
386 Virtual device driver Windows 16-bit Executables
HT? HTML Document Possibly contains JavaScript
HTML HTML Document Possibly contains JavaScript

Unsorted:

Extension Description Note
PRC PalmOS application
PDB PalmOS Database

Applications for Windows:

Extension Description Note
ADP Microsoft Access Project
ASD MS Word Auto-backup file Possibly contains macros (VBScript)
CDR Corel Draw vector graphics
CNV MS Word Data conversion support file
D?B AutoCad
DOC MS Word Document Possibly contains macros (VBScript)
DOT MS Word Document template Possibly contains macros (VBScript)
DVB AutoCAD Project files
DWG Autocad Drawing files Possibly contains macros (VBScript)
GMS Corel products Global Macro Storage
MD? MS Access Office database files Possibly contains macros (VBScript)
MDE MS Access MDE Database Possibly contains macros (VBScript)
MPD MS Project Database file Possibly contains macros (VBScript)
MPP MS Project 98 Document Possibly contains macros (VBScript)
MPT MS Project 98 Template Possibly contains macros (VBScript)
MSG Outlook message files Possibly contains macros (VBScript)
MSO MS Office 2000 files saved as HTML Possibly contains JavaScript
OBZ MS Binder Wizard Possibly contains macros (VBScript)
OCX Active-X OLE control
OLB OLE Object Library
OLE OLE Object
OTM MS Outlok macro (VBA) storage Possibly contains macros (VBScript)
POT MS PowerPoint presentation template Possibly contains macros (VBScript)
PPS MS PowerPoint show Possibly contains macros (VBScript)
PP? MS PowerPoint presentations Office Possibly contains macros (VBScript)
PWZ MS PowerPoint Wizard Possibly contains macros (VBScript)
RTF MS Rich text format (embedded and renamed OLE2)
SHW Corel Presentation Show
SMM AMI Pro macro file Possibly contains macros (VBScript)
TLB OLE library file
VS? MS Visio documents Possibly contains macros (VBScript)
WBK MS Office workbook
WIZ Microsoft wizards Possibly contains macros (VBScript)
WPD Corel WordPerfect 9 with VBA Possibly contains macros (VBScript)
WPT WordPerfect Document Template
WRI MS Write
XLB MS Excel Worksheet Possibly contains macros (VBScript)
XL? MS Excel Spreadsheet Possibly contains macros (VBScript)
XLT MS Excel Spreadsheet Template Possibly contains macros (VBScript)

Archives and compressed files:

Extension Description Note
ACE ACE Archiver file
AIN AIN-compressed file
ARC PKARC Archiver file
ARJ ARJ Archiver file Holds also for extensions .A0?, .A1? etc.
B64 Encoded base64 MIME archive
BO? Boot sector image
BZ BZIP compressed file
BZ2 BZIP2 compressed file
CAB MS Cabinet file
CAR Crypted Archive
COM Self-extracting archives
COM DIET, PKLITE, CRYPTCOM, ICE etc.
CPIO Unix Archive file
CPT Compressed MAC file
EXE DIET, PKLITE, LZEXE, UPX etc.
GZ GZIP compressed
ICE ICE compressed
IM? Disk image
JAR Java Archive
LIM Limit compressed
LZH LHA compressed
MSI MS Windows Installer file
PAK PkPak compressed
RAR RAR compressed Holds also for extensions .R0?, .R1? etc.
TAR Unix TAR compressed
TAZ Unix Compressed TAR file
TD0 TeleDisk diskette images
UU UUEncoded Unix file
UUE UUEncode
Z Unix Compress file
ZIP PKZIP, WinZip
ZOO ZOO Compress file
??_ MS Compress/Expand

Related references

Main page
Introduction to the antivirus protection