Macro virus

Last updated

In computing terminology, a macro virus is a virus that is written in a macro language: a programming language which is embedded inside a software application (e.g., word processors and spreadsheet applications). Some applications, such as Microsoft Office, Excel, PowerPoint allow macro programs to be embedded in documents such that the macros are run automatically when the document is opened, and this provides a distinct mechanism by which malicious computer instructions can spread. This is one reason it can be dangerous to open unexpected attachments in e-mails. Many antivirus programs can detect macro viruses; however, the macro virus' behavior can still be difficult to detect.

Contents

Fundamentals

A macro is a series of commands and actions that helps automating some tasks - usually a quite short and simple program. However they are created, they need to be executed by some system which interprets the stored commands. Some macro systems are self-contained programs, but others are built into complex applications (for example word processors) to allow users to repeat sequences of commands easily, or to allow developers to tailor the application to local needs.

Operation

A macro virus can be spread through e-mail attachments, removable media, networks and the Internet, and is notoriously difficult to detect. [1] A common way for a macro virus to infect a computer is by replacing normal macros with a virus. The macro virus replaces regular commands with the same name and runs when the command is selected. These malicious macros may start automatically when a document is opened or closed, without the user's knowledge. [2]

Once a file containing a macro virus is opened, the virus can infect the system. When triggered, it will begin to embed itself in other documents and templates. It may corrupt other parts of the system, depending on what resources a macro in this application can access. When the infected documents are shared with other users and systems, the virus spreads. Macro viruses have been used as a method of installing software on a system without the user's consent, as they can be used to download and install software from the internet through the use of automated key-presses. However, this is uncommon as it is usually not fruitful for the virus coder since the installed software is usually noticed and uninstalled by the user. [3]

Since a macro virus depends on the application rather than the operating system, it can infect a computer running any operating system to which the targeted application has been ported. In particular, since Microsoft Word is available on Macintosh computers, word macro viruses can attack some Macs in addition to Windows platforms. [1]

An example of a macro virus is the Melissa virus which appeared in March 1999. When a user opens a Microsoft Word document containing the Melissa virus, their computer becomes infected. The virus then sends itself by email to the first 50 people in the person's address book. This made the virus replicate at a fast rate. [4]

Not all macro viruses are detected by antivirus software. [5] Caution when opening email attachments and other documents decreases the chance of becoming infected.

Due to the prevalence of macro viruses, starting with Microsoft Office 2007, Microsoft assigned a separate set of file extensions ending in "m" to Office files containing macros in order to prevent users from opening macro virus-infected files that were not intended to contain macros in the first place. [6]

Current versions of Microsoft Office block macros by default in files originating from the internet, a change that first appeared in April 2022. [7]

See also

Related Research Articles

Malware is any software intentionally designed to cause disruption to a computer, server, client, or computer network, leak private information, gain unauthorized access to information or systems, deprive access to information, or which unknowingly interferes with the user's computer security and privacy. Researchers tend to classify malware into one or more sub-types.

Spyware is any software with malicious behavior that aims to gather information about a person or organization and send it to another entity in a way that harms the user by violating their privacy, endangering their device's security, or other means. This behavior may be present in malware and in legitimate software. Websites may engage in spyware behaviors like web tracking. Hardware devices may also be affected.

<span class="mw-page-title-main">Timeline of computer viruses and worms</span> Computer malware timeline

This timeline of computer viruses and worms presents a chronological timeline of noteworthy computer viruses, computer worms, Trojan horses, similar malware, related research and events.

<span class="mw-page-title-main">Antivirus software</span> Computer software to defend against malicious computer viruses

Antivirus software, also known as anti-malware, is a computer program used to prevent, detect, and remove malware.

Linux malware includes viruses, Trojans, worms and other types of malware that affect the Linux family of operating systems. Linux, Unix and other Unix-like computer operating systems are generally regarded as very well-protected against, but not immune to, computer viruses.

<span class="mw-page-title-main">ClamAV</span> Open-source antivirus software

ClamAV (antivirus) is a free software, cross-platform antimalware toolkit able to detect many types of malware, including viruses. It was developed for Unix and has third party versions available for AIX, BSD, HP-UX, Linux, macOS, OpenVMS, OSF (Tru64), Solaris and Haiku. As of version 0.97.5, ClamAV builds and runs on Microsoft Windows. Both ClamAV and its updates are made available free of charge. One of its main uses is on mail servers as a server-side email virus scanner.

Scareware is a form of malware which uses social engineering to cause shock, anxiety, or the perception of a threat in order to manipulate users into buying unwanted software. Scareware is part of a class of malicious software that includes rogue security software, ransomware and other scam software that tricks users into believing their computer is infected with a virus, then suggests that they download and pay for fake antivirus software to remove it. Usually the virus is fictional and the software is non-functional or malware itself. According to the Anti-Phishing Working Group, the number of scareware packages in circulation rose from 2,850 to 9,287 in the second half of 2008. In the first half of 2009, the APWG identified a 585% increase in scareware programs.

Norton AntiVirus is an anti-virus or anti-malware software product founded by Peter Norton, developed and distributed by Symantec since 1990 as part of its Norton family of computer security products. It uses signatures and heuristics to identify viruses. Other features included in it are e-mail spam filtering and phishing protection.

<span class="mw-page-title-main">WinFixer</span> Rogue security software

WinFixer was a family of scareware rogue security programs developed by Winsoftware which claimed to repair computer system problems on Microsoft Windows computers if a user purchased the full version of the software. The software was mainly installed without the user's consent. McAfee claimed that "the primary function of the free version appears to be to alarm the user into paying for registration, at least partially based on false or erroneous detections." The program prompted the user to purchase a paid copy of the program.

Rogue security software is a form of malicious software and internet fraud that misleads users into believing there is a virus on their computer and aims to convince them to pay for a fake malware removal tool that actually installs malware on their computer. It is a form of scareware that manipulates users through fear, and a form of ransomware. Rogue security software has been a serious security threat in desktop computing since 2008. An early example that gained infamy was SpySheriff and its clones, such as Nava Shield.

Defensive computing is a form of practice for computer users to help reduce the risk of computing problems, by avoiding dangerous computing practices. The primary goal of this method of computing is to be able to anticipate and prepare for potentially problematic situations prior to their occurrence, despite any adverse conditions of a computer system or any mistakes made by other users. This can be achieved through adherence to a variety of general guidelines, as well as the practice of specific computing techniques.

A zero-day is a vulnerability or security hole in a computer system unknown to its owners, developers or anyone capable of mitigating it. Until the vulnerability is remedied, threat actors can exploit it in a zero-day exploit, or zero-day attack.

<span class="mw-page-title-main">Computer virus</span> Computer program that modifies other programs to replicate itself and spread

A computer virus is a type of malware that, when executed, replicates itself by modifying other computer programs and inserting its own code into those programs. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses.

MS Antivirus is a scareware rogue anti-virus which purports to remove virus infections found on a computer running Microsoft Windows. It attempts to scam the user into purchasing a "full version" of the software. The company and the individuals behind Bakasoftware operated under other different 'company' names, including Innovagest2000, Innovative Marketing Ukraine, Pandora Software, LocusSoftware, etc.

AV Security Suite is a type of rogue security software, commonly categorized as scareware and malware, which masquerades as a legitimate virus scanner on the victim's Microsoft Windows system. While it is predominantly observed on Windows platforms, it may adopt alternative names on other operating systems to better integrate itself within their interfaces, thereby enhancing its deceptive nature. In the task manager, the program typically appears as a series of seemingly random characters followed by identifiers such as "tssd.exe" or "shdw.exe," a tactic aimed at complicating detection and removal efforts.

Sality is the classification for a family of malicious software (malware), which infects Microsoft Windows systems files. Sality was first discovered in 2003 and has advanced to become a dynamic, enduring and full-featured form of malicious code. Systems infected with Sality may communicate over a peer-to-peer (P2P) network to form a botnet to relay spam, proxying of communications, exfiltrating sensitive data, compromising web servers and/or coordinating distributed computing tasks to process intensive tasks. Since 2010, certain variants of Sality have also incorporated rootkit functions as part of an ongoing evolution of the malware family. Because of its continued development and capabilities, Sality is considered one of the most complex and formidable forms of malware to date.

Slenfbot is the classification for a family of malicious software (malware), which infects files on Microsoft Windows systems. Slenfbot was first discovered in 2007 and, since then, numerous variants have followed; each with slightly different characteristics and new additions to the worm's payload, such as the ability to provide the attacker with unauthorized access to the compromised host. Slenfbot primarily spreads by luring users to follow links to websites, which contain a malicious payload. Slenfbot propagates via instant messaging applications, removable drives and/or the local network via network shares. The code for Slenfbot appears to be closely managed, which may provide attribution to a single group and/or indicate that a large portion of the code is shared amongst multiple groups. The inclusion of other malware families and variants as well as its own continuous evolution, makes Slenfbot a highly effective downloader with a propensity to cause even more damage to compromised systems.

Win32/Patched is a computer Trojan targeting the Microsoft Windows operating system that was first detected in October 2008. Files detected as "Trojan.Win32.Patched" are usually Windows components that are patched by a malicious application. The purpose of patching varies. For example, certain malware patches system components in order to disable security, such as the Windows Safe File Check feature. Other malware can add parts of its code to a system component and then patch certain functions of the original file to point to an appended code.

Dridex, also known as Bugat and Cridex, is a form of malware that specializes in stealing bank credentials via a system that utilizes macros from Microsoft Word.

<span class="mw-page-title-main">Locky</span>

Locky is ransomware malware released in 2016. It is delivered by email with an attached Microsoft Word document that contains malicious macros. When the user opens the document, it appears to be full of gibberish, and includes the phrase "Enable macro if data encoding is incorrect," a social engineering technique. If the user does enable macros, they save and run a binary file that downloads the actual encryption Trojan, which will encrypt all files that match particular extensions. Filenames are converted to a unique 16 letter and number combination. Initially, only the .locky file extension was used for these encrypted files. Subsequently, other file extensions have been used, including .zepto, .odin, .aesir, .thor, and .zzzzz. After encryption, a message instructs them to download the Tor browser and visit a specific criminal-operated Web site for further information.

References

  1. 1 2 "Frequently Asked Questions: Word Macro Viruses". Microsoft. Archived from the original on 2011-06-04. Retrieved 2006-06-18.
  2. "Information Bulletin: Macro Virus Update". Computer Incident Advisory Capability. Archived from the original on 2006-06-12. Retrieved 2006-06-18.
  3. Margaret Rouse (January 2018). "macro virus" . Retrieved 7 January 2019.
  4. "How Computer Viruses Work". How Stuff Works inc. April 2000. Retrieved 2006-06-18.
  5. Frankenfield, Jake. "Macro Virus". Investopedia. Retrieved 12 January 2022.
  6. Hoffman, Chris. "Macros Explained: Why Microsoft Office Files Can Be Dangerous". How-To Geek. Retrieved 2 March 2021.
  7. DHB-MSFT. "Macros from the internet are blocked by default in Office - Deploy Office". docs.microsoft.com. Retrieved 2022-02-15.

Further reading