Symantec has issued a patch for a hole in its anti-virus software that could allow unauthorised access to a company's servers.

The flaw, in version 9 of its AntiVirus Corporate Edition product, exposes the server login name and password used by the administrator who authorises updates to the software, Symantec said.

The product comes with a LiveUpdate client that can be set to check for product updates. After the client receives the updates from the LiveUpdate server, information about the transaction is stored in a local log file. The LiveUpdate server login and password are included in that log file as clear text, Symantec said.

The file is accessible to all users on the system, meaning workers across the enterprise could view the login name and password. The danger is most apparent if that same login and password are used for accessing other, more critical corporate systems.

The problem was first identified last week in a posting on Bugtraq. Symantec issued the patch late Friday.

Symantec has advised customers to create a unique login and password for accessing LiveUpdate services, rather than using the same administrator login that provides broader system access.