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Possible to abuse the sections in which are excluded from signature check in a signed executable?
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<blockquote data-quote="Trident" data-source="post: 1039918" data-attributes="member: 99014"><p>I am not sure also to what extent signed malware is a problem. Although for performance reasons signed malware may be almost invisible (for example excluded from antivirus scanning after one verification, whitelisted from behavioural blocking or under reduced monitoring). These are some of the ways it can bypass defences. But it is normally short-lived. It won’t take extremely long before vendors update their certificate revocation list.</p><p></p><p>The biggest problem now (although not a novel tactic) seems to be <a href="https://attack.mitre.org/techniques/T1027/001/" target="_blank">Mitre T1027</a> signed + inflated (padded) or just padded and placed in a password protected archive — this bypasses static analysis, emulation and many other layers effectively and prevents transmission to vendors (both from the product and from crawlers). Technologies such as CrowdStrike Falcon Sandbox, Symantec Cynic, Check Point threat emulation and Defender cloud ML are extremely effective and well researched but can’t handle files above certain size (usually 50MB).</p><p>Only once the payload is extracted in memory, certain technologies may react.</p><p>For example CozyBear have been using this tactic at least a few years now + other tactics like <a href="https://www.crowdfundinsider.com/2019/01/143342-russian-malware-infected-movie-file-used-to-steal-cryptocurrencies-rip-off-wikipedia/amp/" target="_blank">creating fake PirateBay dupes</a> (pushing “movies” that were a year ago 700 mb executable), using <a href="https://cloudsek.com/blog/threat-actors-abuse-ai-generated-youtube-videos-to-spread-stealer-malware" target="_blank">CEO poisoning, AI-Generated YT tutorials on how to download illegal software,</a> using certificates obtained from breaches and others. It all ends with crypto-extortion and other theft.</p><p></p><p>In the case of installers, this might be used in a highly-fragmented attack (some behavioural blockers are not great against these). But there are many other ways code can be smuggled as well.</p></blockquote><p></p>
[QUOTE="Trident, post: 1039918, member: 99014"] I am not sure also to what extent signed malware is a problem. Although for performance reasons signed malware may be almost invisible (for example excluded from antivirus scanning after one verification, whitelisted from behavioural blocking or under reduced monitoring). These are some of the ways it can bypass defences. But it is normally short-lived. It won’t take extremely long before vendors update their certificate revocation list. The biggest problem now (although not a novel tactic) seems to be [URL='https://attack.mitre.org/techniques/T1027/001/']Mitre T1027[/URL] signed + inflated (padded) or just padded and placed in a password protected archive — this bypasses static analysis, emulation and many other layers effectively and prevents transmission to vendors (both from the product and from crawlers). Technologies such as CrowdStrike Falcon Sandbox, Symantec Cynic, Check Point threat emulation and Defender cloud ML are extremely effective and well researched but can’t handle files above certain size (usually 50MB). Only once the payload is extracted in memory, certain technologies may react. For example CozyBear have been using this tactic at least a few years now + other tactics like [URL='https://www.crowdfundinsider.com/2019/01/143342-russian-malware-infected-movie-file-used-to-steal-cryptocurrencies-rip-off-wikipedia/amp/']creating fake PirateBay dupes[/URL] (pushing “movies” that were a year ago 700 mb executable), using [URL='https://cloudsek.com/blog/threat-actors-abuse-ai-generated-youtube-videos-to-spread-stealer-malware']CEO poisoning, AI-Generated YT tutorials on how to download illegal software,[/URL] using certificates obtained from breaches and others. It all ends with crypto-extortion and other theft. In the case of installers, this might be used in a highly-fragmented attack (some behavioural blockers are not great against these). But there are many other ways code can be smuggled as well. [/QUOTE]
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