Ransomware.
rule win_knot_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.knot." 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.knot" malpedia_rule_date = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { e8???????? 83c404 6808020000 8d95f0fdffff } // n = 4, score = 200 // e8???????? | // 83c404 | add esp, 4 // 6808020000 | push 0x208 // 8d95f0fdffff | lea edx, [ebp - 0x210] $sequence_1 = { 83c404 68???????? ff15???????? e9???????? 8d95f4fdffff 52 } // n = 6, score = 200 // 83c404 | add esp, 4 // 68???????? | // ff15???????? | // e9???????? | // 8d95f4fdffff | lea edx, [ebp - 0x20c] // 52 | push edx $sequence_2 = { 8d85a0fbffff 50 68???????? ff15???????? 89858cf9ffff 83bd8cf9ffffff } // n = 6, score = 200 // 8d85a0fbffff | lea eax, [ebp - 0x460] // 50 | push eax // 68???????? | // ff15???????? | // 89858cf9ffff | mov dword ptr [ebp - 0x674], eax // 83bd8cf9ffffff | cmp dword ptr [ebp - 0x674], -1 $sequence_3 = { 51 ff15???????? 8d95d8feffff 52 8b85d4feffff } // n = 5, score = 200 // 51 | push ecx // ff15???????? | // 8d95d8feffff | lea edx, [ebp - 0x128] // 52 | push edx // 8b85d4feffff | mov eax, dword ptr [ebp - 0x12c] $sequence_4 = { 6a04 8b45ec 50 ff15???????? 8945fc 837dfc00 } // n = 6, score = 200 // 6a04 | push 4 // 8b45ec | mov eax, dword ptr [ebp - 0x14] // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax // 837dfc00 | cmp dword ptr [ebp - 4], 0 $sequence_5 = { 51 6a08 8d95c8fdffff 52 8b45f0 50 ff15???????? } // n = 7, score = 200 // 51 | push ecx // 6a08 | push 8 // 8d95c8fdffff | lea edx, [ebp - 0x238] // 52 | push edx // 8b45f0 | mov eax, dword ptr [ebp - 0x10] // 50 | push eax // ff15???????? | $sequence_6 = { 6a01 8b4df4 51 ff15???????? 85c0 7507 32c0 } // n = 7, score = 200 // 6a01 | push 1 // 8b4df4 | mov ecx, dword ptr [ebp - 0xc] // 51 | push ecx // ff15???????? | // 85c0 | test eax, eax // 7507 | jne 9 // 32c0 | xor al, al $sequence_7 = { 8d8d90f9ffff 51 e8???????? 83c408 8d9580f7ffff } // n = 5, score = 200 // 8d8d90f9ffff | lea ecx, [ebp - 0x670] // 51 | push ecx // e8???????? | // 83c408 | add esp, 8 // 8d9580f7ffff | lea edx, [ebp - 0x880] $sequence_8 = { 85c0 7507 32c0 e9???????? c785d8fdffff00000000 8d85d8fdffff } // n = 6, score = 200 // 85c0 | test eax, eax // 7507 | jne 9 // 32c0 | xor al, al // e9???????? | // c785d8fdffff00000000 | mov dword ptr [ebp - 0x228], 0 // 8d85d8fdffff | lea eax, [ebp - 0x228] $sequence_9 = { 51 ff15???????? 85c0 0f840e020000 6880000000 8d9580f7ffff } // n = 6, score = 200 // 51 | push ecx // ff15???????? | // 85c0 | test eax, eax // 0f840e020000 | je 0x214 // 6880000000 | push 0x80 // 8d9580f7ffff | lea edx, [ebp - 0x880] condition: 7 of them and filesize < 59392 }
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