Actor(s): APT28
Suspected Zebrocy loader written in Nim.
rule win_unidentified_078_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.unidentified_078." 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.unidentified_078" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" 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 = { 0f8412010000 0f8cee000000 80fa0d 0f8421010000 80fa1b 0f8576010000 } // n = 6, score = 200 // 0f8412010000 | mov ecx, eax // 0f8cee000000 | dec eax // 80fa0d | add esp, 0x28 // 0f8421010000 | dec eax // 80fa1b | mov ecx, eax // 0f8576010000 | dec eax $sequence_1 = { 0f8d94010000 80fa26 0f8f18010000 80fa23 0f8d82010000 } // n = 5, score = 200 // 0f8d94010000 | jmp 0x416 // 80fa26 | call dword ptr [edi + ebx*8] // 0f8f18010000 | dec eax // 80fa23 | lea esi, [eax - 1] // 0f8d82010000 | jmp 0x436 $sequence_2 = { 80fa5c 0f94c1 80fa2f 0f94c2 08d1 } // n = 5, score = 200 // 80fa5c | mov eax, edx // 0f94c1 | not eax // 80fa2f | inc ecx // 0f94c2 | and eax, dword ptr [ecx + 0x1014] // 08d1 | dec ecx $sequence_3 = { 3c18 0f8483000000 3c1c 740d 3c16 } // n = 5, score = 200 // 3c18 | mov dword ptr [esp + 0x20], 0 // 0f8483000000 | dec ecx // 3c1c | mov eax, ecx // 740d | xor ecx, ecx // 3c16 | mov dword ptr [esp + 0x20], 0 $sequence_4 = { e9???????? 80fa0c 0f8412010000 0f8cee000000 80fa0d } // n = 5, score = 200 // e9???????? | // 80fa0c | lea esi, [0x7067] // 0f8412010000 | mov ecx, 7 // 0f8cee000000 | dec eax // 80fa0d | add edx, 0x1c $sequence_5 = { 89d6 0f883a020000 80fa21 0f8f8f000000 80fa20 0f8d28020000 } // n = 6, score = 200 // 89d6 | inc ecx // 0f883a020000 | mov esp, 0xa // 80fa21 | je 0x18fb // 0f8f8f000000 | dec ecx // 80fa20 | mov eax, dword ptr [ecx] // 0f8d28020000 | dec eax $sequence_6 = { a910000108 753f a900004011 7521 a900000600 7467 } // n = 6, score = 200 // a910000108 | test eax, eax // 753f | dec eax // a900004011 | lea ecx, [0x77b8] // 7521 | dec eax // a900000600 | test eax, eax // 7467 | dec eax $sequence_7 = { ff15???????? 85c0 740e e8???????? 31d2 89c1 e8???????? } // n = 7, score = 200 // ff15???????? | // 85c0 | dec eax // 740e | sub esp, 0x28 // e8???????? | // 31d2 | inc ecx // 89c1 | mov ecx, 4 // e8???????? | $sequence_8 = { b901010000 ff15???????? 85c0 740e } // n = 4, score = 200 // b901010000 | mov ecx, eax // ff15???????? | // 85c0 | cmp ecx, 7 // 740e | ja 0xfe $sequence_9 = { 0f8421010000 80fa1b 0f8576010000 ba02000000 e8???????? } // n = 5, score = 200 // 0f8421010000 | sub edx, eax // 80fa1b | dec ecx // 0f8576010000 | lea ebx, [ecx + esi] // ba02000000 | dec esp // e8???????? | condition: 7 of them and filesize < 688128 }
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