Actor(s): Turla
Talos describes this as a malware family with very scoped functionality and thus a small code footprint, likely used as a second chance backdoor.
rule win_tiny_turla_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.tiny_turla." 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.tiny_turla" 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 = { 44897e30 895624 85d2 0f851dfdffff 8b4e08 ff15???????? } // n = 6, score = 100 // 44897e30 | lea eax, [edx + 0x18] // 895624 | mov ecx, 0x40 // 85d2 | dec eax // 0f851dfdffff | mov ebx, edx // 8b4e08 | inc ecx // ff15???????? | $sequence_1 = { 0f84f8000000 33d2 488d4da0 448d4268 } // n = 4, score = 100 // 0f84f8000000 | lea edx, [eax + 1] // 33d2 | je 0xeb // 488d4da0 | inc esp // 448d4268 | mov esi, dword ptr [ebp + 0x67] $sequence_2 = { 448d4268 e8???????? 33d2 c745af68000000 488d4d8f } // n = 5, score = 100 // 448d4268 | test eax, eax // e8???????? | // 33d2 | jne 0xafd // c745af68000000 | dec eax // 488d4d8f | mov ecx, dword ptr [ebp + 0x30] $sequence_3 = { ff15???????? 85c0 0f84b2feffff b801000000 4c8d9c24e0000000 498b5b20 } // n = 6, score = 100 // ff15???????? | // 85c0 | dec esp // 0f84b2feffff | mov edx, eax // b801000000 | dec eax // 4c8d9c24e0000000 | test eax, eax // 498b5b20 | je 0xa48 $sequence_4 = { 488d4c2450 e8???????? b801000000 488b9c2430010000 4881c4f0000000 415f } // n = 6, score = 100 // 488d4c2450 | dec eax // e8???????? | // b801000000 | lea ecx, [esp + 0x20] // 488b9c2430010000 | dec eax // 4881c4f0000000 | mov esi, dword ptr [esp + 0x58] // 415f | xor edi, edi $sequence_5 = { 4803cb e8???????? 488b4dd0 4c8d4528 488d1595090000 } // n = 5, score = 100 // 4803cb | mov dword ptr [ebx], ecx // e8???????? | // 488b4dd0 | lea edx, [edi + edi] // 4c8d4528 | mov ebx, edi // 488d1595090000 | dec eax $sequence_6 = { 66894308 488d5b10 413bfe 72d3 488d5e18 488bcb } // n = 6, score = 100 // 66894308 | inc ebp // 488d5b10 | xor ecx, ecx // 413bfe | dec eax // 72d3 | mov dword ptr [esp + 0x58], 0xffffffff // 488d5e18 | dec esp // 488bcb | lea eax, [ebp - 0x80] $sequence_7 = { 488bcf ff15???????? 48894587 4885c0 0f8486000000 448b7567 41d1ee } // n = 7, score = 100 // 488bcf | lea edx, [0x982] // ff15???????? | // 48894587 | test eax, eax // 4885c0 | je 0x975 // 0f8486000000 | dec eax // 448b7567 | mov ecx, dword ptr [ebp - 0x30] // 41d1ee | dec esp $sequence_8 = { 488d4dd8 e8???????? 488d4de0 e8???????? 33c0 4883c450 } // n = 6, score = 100 // 488d4dd8 | jne 0x186 // e8???????? | // 488d4de0 | dec eax // e8???????? | // 33c0 | lea ecx, [esp + 0x50] // 4883c450 | inc esp $sequence_9 = { 4803ca ffe1 488bcf e8???????? 413bc6 7407 } // n = 6, score = 100 // 4803ca | lea eax, [edx + 0x18] // ffe1 | dec eax // 488bcf | lea eax, [ebp - 0x71] // e8???????? | // 413bc6 | dec eax // 7407 | lea ecx, [ebp - 0x60] condition: 7 of them and filesize < 51200 }
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