Delphi-based ransomware.
rule win_vegalocker_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2020-10-14" version = "1" description = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.5.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.vegalocker" malpedia_rule_date = "20201014" malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9" malpedia_version = "20201014" 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 = { 8bcf e8???????? 8d45c0 33c9 ba20000000 e8???????? } // n = 6, score = 300 // 8bcf | mov ecx, edi // e8???????? | // 8d45c0 | lea eax, [ebp - 0x40] // 33c9 | xor ecx, ecx // ba20000000 | mov edx, 0x20 // e8???????? | $sequence_1 = { e8???????? 83fb10 7f25 b800010000 } // n = 4, score = 300 // e8???????? | // 83fb10 | cmp ebx, 0x10 // 7f25 | jg 0x27 // b800010000 | mov eax, 0x100 $sequence_2 = { 8d55e0 b908000000 8bc3 e8???????? } // n = 4, score = 300 // 8d55e0 | lea edx, [ebp - 0x20] // b908000000 | mov ecx, 8 // 8bc3 | mov eax, ebx // e8???????? | $sequence_3 = { 8d45fc e8???????? 83fb10 7f25 } // n = 4, score = 300 // 8d45fc | lea eax, [ebp - 4] // e8???????? | // 83fb10 | cmp ebx, 0x10 // 7f25 | jg 0x27 $sequence_4 = { 8b40f4 83c00c e8???????? 8bd0 8b4508 } // n = 5, score = 300 // 8b40f4 | mov eax, dword ptr [eax - 0xc] // 83c00c | add eax, 0xc // e8???????? | // 8bd0 | mov edx, eax // 8b4508 | mov eax, dword ptr [ebp + 8] $sequence_5 = { 83ee04 8b36 8d45f0 e8???????? 8bd0 8bce 8bc3 } // n = 7, score = 300 // 83ee04 | sub esi, 4 // 8b36 | mov esi, dword ptr [esi] // 8d45f0 | lea eax, [ebp - 0x10] // e8???????? | // 8bd0 | mov edx, eax // 8bce | mov ecx, esi // 8bc3 | mov eax, ebx $sequence_6 = { 33d2 8b45f0 8b08 ff5118 } // n = 4, score = 300 // 33d2 | xor edx, edx // 8b45f0 | mov eax, dword ptr [ebp - 0x10] // 8b08 | mov ecx, dword ptr [eax] // ff5118 | call dword ptr [ecx + 0x18] $sequence_7 = { 8b48f8 8b4508 8b50fc 8d45f4 e8???????? 8b45f4 } // n = 6, score = 300 // 8b48f8 | mov ecx, dword ptr [eax - 8] // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b50fc | mov edx, dword ptr [eax - 4] // 8d45f4 | lea eax, [ebp - 0xc] // e8???????? | // 8b45f4 | mov eax, dword ptr [ebp - 0xc] $sequence_8 = { 6a20 8b45e8 e8???????? 50 e8???????? } // n = 5, score = 300 // 6a20 | push 0x20 // 8b45e8 | mov eax, dword ptr [ebp - 0x18] // e8???????? | // 50 | push eax // e8???????? | $sequence_9 = { 8b40f4 83c00c e8???????? 8bd0 } // n = 4, score = 300 // 8b40f4 | mov eax, dword ptr [eax - 0xc] // 83c00c | add eax, 0xc // e8???????? | // 8bd0 | mov edx, eax condition: 7 of them and filesize < 1654784 }
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