31 lines
995 B
Text
31 lines
995 B
Text
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rule SUSP_NET_Msil_Suspicious_Use_StrReverse {
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meta:
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/*
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This combination of imports and usage of StrReverse appears often
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in .NET crypters and malware trying to evade static string analysis
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*/
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description = "Detects mixed use of Microsoft.CSharp and VisualBasic to use StrReverse"
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author = "dr4k0nia, modified by Florian Roth"
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reference = "https://github.com/dr4k0nia/yara-rules"
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version = "1.1"
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date = "01/31/2023"
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modified = "02/22/2023"
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score = 70
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hash = "02ce0980427dea835fc9d9eed025dd26672bf2c15f0b10486ff8107ce3950701"
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id = "830dec40-4412-59c1-8b4d-a237f14acd30"
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strings:
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$a1 = ", PublicKeyToken="
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$a2 = ".NETFramework,Version="
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$csharp = "Microsoft.CSharp"
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$vbnet = "Microsoft.VisualBasic"
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$strreverse = "StrReverse"
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condition:
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uint16(0) == 0x5a4d
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and filesize < 50MB
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and all of ($a*)
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and $csharp
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and $vbnet
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and $strreverse
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}
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