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WinRAR security flaw

Many litigation support professionals will have had occasion to install and use the file compression software, WinRAR. WinRAR can compress files in the zip format and extract files in several compression formats.

This past February a security flaw was found in WinRAR that can be exploited to gain control over a user's computer. WinRAR uses a .dll file (named, unacev2.dll) to open ACE files. ACE is a file compression format that was most popular around 2000. WinRAR's dynamic link library does not have adequate protection, and can be used to extract a file to the Windows startup folder. A file named, CMSTray.exe, is extracted there, and is then used to download the Cobalt Strike Beacon pen testing tool. This can give a malicious outside user the ability to control your computer.

The updated version of WinRAR addresses the vulnerability, but it's best to exercise caution when using WinRAR or working with ACE files. WinRAR has been used to distribute malware in other ways. Many anti-virus programs do not adequately protect against the vulnerabilities of ACE files.

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