Setting Real-time Scan compression layers

Trend Micro PC-cillin

Setting Real-time Scan compression layers

PC-cillin recognizes many types of file compression including PK-ZIP and LZEXE, and four types of file encoding, including UUencode and MIME. File compression involves shrinking the size of a file or files using a data compression format. One of the most popular is the Zip format. Compressed files are useful for transferring information over networks because of the smaller file size.

PC-cillin will check the contents of a compressed file for viruses based on the number of layers you have set. Usually when files are compressed they are only compressed to the first layer: (docs.zip{A.doc, B.doc, C.doc, D.doc, E.doc}) i.e., the compressed file (docs.zip) contains the files (A.doc, B.doc, C.doc, D.doc, E.doc) which are located in the first layer. If the docs.zip file was compressed again [docs+1.zip(docs.zip{A.doc, B.doc, C.doc, D.doc, E.doc})], the original files are now located in the second layer.

When multiple layers of compression are encountered, PC-cillin recursively decompresses each, up to the limit you set. In other words, if an archive contains .cab files that have been compressed using PK-ZIP, and LZEXE, PK-LITE, Microsoft Compress, etc., PC-cillin will decompress each layer until no more compressed files are found or the limit of you have specified is reached.

To set Real-time Scan compression layers:

  1. On the PC-cillin window, click Settings. The Settings window appears.

  2. On the Settings menu, click the Virus Scan link. The menu expands.

  3. Click the Real-time Scan link. The Real-time Scan screen appears.

  4. Under Scan file types, select the number of compression layers from the Compression Layer list. The default number of layers is one.

  5. Click Apply.

Note: When detecting infected files that are part of a compressed file, PC-cillin can automatically execute the Clean action only if the following conditions are met:

  • You have selected the Clean viruses in compressed files check box.

  • The file or files are located in the second layer.

To perform a Clean scan action for a compressed file for files beyond the second layer, you must decompress it first. If you have Real-time Scan enabled, decompressing the file will trigger the action.

If you're not using Real-time Scan, right-click the infected file after it is decompressed, select Properties from the pop-up menu and then choose Virus Properties.

Important: Be sure to delete the compressed file (for example the .ZIP file), because it will still contain a copy of the infected item.

See also:

About virus scan actions

About Real-time Scan

Enabling Real-time Scan

Selecting Real-time Scan file types

Adding Real-time Scan tile types

About Exception files