Open Source Risk Management (OSRM) claims to have identified 27 Microsoft patents which could cover technologies in the kernel, from a total 287 patents altogether. OSRM’s study of the kernel discovered 98 patents owned by so-called Linux-friendly companies.

The remainder of the patents are owned by various entities whose attitude to open source is unknown.

None of the patents covering the technologies found in the kernel have been tested in court, OSRM said. The kernel did not contain any technology covered by court validated patents, the organization found.

OSRM believes Linux suppliers are at risk if the owners of the patents decide to cash-in, saddling software and systems companies with expensive legal actions in the process. The size of most patent actions is between $2m and $4m according to OSRM, who from next January will provide indemnification services for Linux companies.

The threat of legal action is very real, as proved by SCO Group Inc. SCO’s predecessor Caldera Systems Inc was an active participant in Linux, with employees contributing code to the kernel before it launched its case against IBM.

SCO is attempting to build a business based on royalties derived from patents it claims to own inside Linux.

Microsoft, meanwhile, is attempting to make more of its own vast portfolio of patents. Last November, Microsoft released its File Allocation Table (FAT) patent under a commercially reasonable, non-exclusive license charging up to $0.25 per unit with a cap of $250,000. At the time, Microsoft said it planned to release 4,000 patents and 5,400 patents pending for licensing.

Chief software architect Bill Gates this week told financial analysts Microsoft expects to file 3,000 patents this year – up from just over 2,000 last year.

OSRM refused to detail which patents are held by Microsoft, or others, but said in publishing its survey it hoped to help prepare companies, so they can take steps to protect themselves.

There is a risk and we are better off knowing about it and dealing with it rather than ignoring it. If you ignore you let the source of the risk take advantage of the timing, said OSRM lead patent counsel and independent patent attorney Dan Ravicher.

Microsoft was unavailable for comment.