Malware authors have increasingly included open-source libraries and other legitimate tools in their malicious creations for the past few years, said Bogdan Botezatu, a senior e-threat analyst at antivirus vendor Bitdefender, via email Monday. This offers several benefits to them including lower development costs and reducing the amount of code that antivirus vendors can sign as malicious, he said.
There have been some cases where the level of misuse of a legitimate tool has been so great that the tool was eventually flagged as malware or riskware by security vendors, because the malicious use cases far exceeded the legitimate ones. However, chances that a popular library like OpenSSL would be blacklisted because of malware abuse are extremely low, Botezatu said. "Common practices in the AV industry demand that malware researchers or automated systems do not sign [as malware] open-source code or freeware libraries."
Botezatu agreed with Greenblatt's advice of signing the third-party libraries distributed with an application. "This minimizes the risk of these libraries getting picked by antivirus solutions and is also a good way to minimize operating system or browser warnings upon download," he said. "However, there is the legal aspect of whether the developer is allowed to distribute the library along with their products or not. Always get written consent before distributing or digitally signing a file."
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