Actor(s): Equation Group
FancyFilter is a piece of code that documents code overlap between frameworks used by Regin and Equation Group.
rule win_fancyfilter_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.fancyfilter." info = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.6.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.fancyfilter" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" /* DISCLAIMER * The strings used in this rule have been automatically selected from the * disassembly of memory dumps and unpacked files, using YARA-Signator. * The code and documentation is published here: * https://github.com/fxb-cocacoding/yara-signator * As Malpedia is used as data source, please note that for a given * number of families, only single samples are documented. * This likely impacts the degree of generalization these rules will offer. * Take the described generation method also into consideration when you * apply the rules in your use cases and assign them confidence levels. */ strings: $sequence_0 = { 740a 66833800 7404 b001 eb02 } // n = 5, score = 400 // 740a | je 0xc // 66833800 | cmp word ptr [eax], 0 // 7404 | je 6 // b001 | mov al, 1 // eb02 | jmp 4 $sequence_1 = { a1???????? 83c012 50 ff15???????? } // n = 4, score = 400 // a1???????? | // 83c012 | add eax, 0x12 // 50 | push eax // ff15???????? | $sequence_2 = { 8b07 83e810 50 83c610 56 } // n = 5, score = 400 // 8b07 | mov eax, dword ptr [edi] // 83e810 | sub eax, 0x10 // 50 | push eax // 83c610 | add esi, 0x10 // 56 | push esi $sequence_3 = { ff15???????? 83c420 83f803 7409 83f806 } // n = 5, score = 400 // ff15???????? | // 83c420 | add esp, 0x20 // 83f803 | cmp eax, 3 // 7409 | je 0xb // 83f806 | cmp eax, 6 $sequence_4 = { 83c012 50 ffd6 a1???????? } // n = 4, score = 400 // 83c012 | add eax, 0x12 // 50 | push eax // ffd6 | call esi // a1???????? | $sequence_5 = { 85c0 750d 8b472c a801 7406 83c804 } // n = 6, score = 400 // 85c0 | test eax, eax // 750d | jne 0xf // 8b472c | mov eax, dword ptr [edi + 0x2c] // a801 | test al, 1 // 7406 | je 8 // 83c804 | or eax, 4 $sequence_6 = { 85c0 740a 66833800 7404 b001 eb02 } // n = 6, score = 400 // 85c0 | test eax, eax // 740a | je 0xc // 66833800 | cmp word ptr [eax], 0 // 7404 | je 6 // b001 | mov al, 1 // eb02 | jmp 4 $sequence_7 = { 81e3ffffff00 ff15???????? 50 ff15???????? } // n = 4, score = 400 // 81e3ffffff00 | and ebx, 0xffffff // ff15???????? | // 50 | push eax // ff15???????? | $sequence_8 = { 85c0 740a 66833800 7404 b001 } // n = 5, score = 400 // 85c0 | test eax, eax // 740a | je 0xc // 66833800 | cmp word ptr [eax], 0 // 7404 | je 6 // b001 | mov al, 1 $sequence_9 = { b805400080 c20400 56 8b742408 } // n = 4, score = 400 // b805400080 | mov eax, 0x80004005 // c20400 | ret 4 // 56 | push esi // 8b742408 | mov esi, dword ptr [esp + 8] condition: 7 of them and filesize < 169984 }
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