Ensuring integrity of sensitive files in file systems is imperative to computer systems. The vast majority of attacks work through unapproved or unauthorized access to sensitive files to take secret data like secret keys, passwords, credit card numbers, and so on. After that, attackers generally conceal their traces by subverting critical files like system logs. File system integrity monitoring is a well-known way to deal with ensuring integrity of sensitive and critical files. The file system is at the heart of any computing system as it stores the data and executable programs. Malicious users or malwares might change the content of a sensitive data file or insert malicious payload in an executable. Hence, monitoring the integrity of the files in the file system is of utmost importance. Significant research work has been done on file integrity monitoring tools. This article presents the currently available tools for file integrity monitoring and their underlying approaches. K E Y W O R D S file integrity monitoring, malware, security, tools, virtualization 1 INTRODUCTION Every modern operating system is backed by a nonvolatile storage system which stores kernel and program executables and other data files including program logs, configurations, and user defined data. Integrity of these files is important for the seamless operation of a system or business. A malicious attacker can modify the content of a file to perform various malicious activities. For example, corrupting a database configuration could result in failure of a database server. Injecting malicious code in an executable could cause erratic behavior during execution. This kind of malicious activities has already been reported by many users. 1 Furthermore, current rapid progression of ransomwares 2 is compromising integrity of sensitive data in large scale. Many business owners, including large private/public organizations, have paid thousands of dollars as ransom. 3 A secured software solution can be useful for early detection of irregular file modification. File Integrity Monitoring (FIM) is an internal control or procedure that performs and demonstrates integrity of files related to the operating system and application software. It compares and verifies the current state and baseline of files. This examination technique regularly includes computing a known cryptographic checksum of the file's original baseline and contrasting that with the present condition of the file. There should be a check on other attributes such as file size, version, modified by, creation date, modified date, IO operations, and cache operations of file to maintain or observe integrity of file. Apart from this, we should also check credentials, privileges and security settings, hash values, and configuration values. Traditionally, file integrity tools (FITs) are used to detect unauthorized file operations in a system. FITs are some software that can monitor file access in a system and trigger appropriate warnings. Much research has been done on file monitoring tools, which di...