Abstract: A method for file conversion that includes receiving a first file in a computer; wherein the first file is of a first format; wherein the computer has a memory having a boot sector, a quarantine sector and a non-quarantine sector; storing the first file at the quarantine sector; wherein the quarantine sector is isolated from the boot sector and the non-quarantine sector, where code in the quarantine sector is prevented from performing write actions on other memory sectors of the memory; checking whether the first file fulfills a set of criteria that comprise: (a) the first file is associated with a valid first digital signature that was generated by a first certificate authority and is of a known format; (b) the first file is about to be converted to a second file of a second format that supports digital signatures; and (c) the first file successfully passed at least one security check; converting the first file to the second file of the second format; generating, by a second certificate authority, a second d

Abstract: A method for malicious hyperlink protection, the method may include receiving, by a risk management computer, a first file that is aimed to a computer of a user; storing the first file in a memory of the risk management computer; searching, by the risk management computer, for a hyperlink that is included in the first file and links to target content that is included in a target website; when finding the hyperlink then evaluating, at least partially by the risk management computer, whether the hyperlink imposes a risk; preventing the user from utilizing the hyperlink for accessing the target content before a completion of the evaluating of whether the hyperlink imposes the risk; and wherein when evaluating that the hyperlink imposes the risk then: modifying the file to provide a modified file; wherein the modifying of the file comprises deleting the hyperlink or replacing the hyperlink with a modified hyperlink; wherein the modified hyperlink links to a web entity that differs from the target website; and sen

Abstract: A method for file conversion that includes receiving a first file in a computer; wherein the first file is of a first format; wherein the computer has a memory having a boot sector, a quarantine sector and a non-quarantine sector; storing the first file at the quarantine sector; wherein the quarantine sector is isolated from the boot sector and the non-quarantine sector, where code in the quarantine sector is prevented from performing write actions on other memory sectors of the memory; checking whether the first file fulfills a set of criteria that comprise: (a) the first file is associated with a valid first digital signature that was generated by a first certificate authority and is of a known format; (b) the first file is about to be converted to a second file of a second format that supports digital signatures; and (c) the first file successfully passed at least one security check; converting the first file to the second file of the second format; generating, by a second certificate authority, a second d

Abstract: A client computer maintains storage of a trusted set of files. For files that the client computer detects that are not part of the trusted set, a server scans copies of files to protect the client computer against malicious software. After scanning, the server sends to the client computer a scan report indicating in which, if any, of the files malicious software was found. The client computer then sets access directives for the files based on the scan report. The system may be configured so that, when the client computer detects a file that is not part of the trusted set, the client computer creates an identifier for the file and sends the identifier to the server. The server can use the file identifier to determine if it has a copy of the file, and only if it does not will it request a copy of the file.