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 = "2026-01-05" 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 = "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 = { c705????????04000000 488bc8 ff15???????? 85c0 742c 488bcb } // n = 6, score = 300 // c705????????04000000 | // 488bc8 | mov eax, edx // ff15???????? | // 85c0 | dec eax // 742c | cmp eax, 0x20 // 488bcb | dec esp $sequence_1 = { 85c0 742c 488bcb e8???????? 488b0d???????? } // n = 5, score = 300 // 85c0 | mov edx, ecx // 742c | dec eax // 488bcb | mov dword ptr [esp + 0x20], eax // e8???????? | // 488b0d???????? | $sequence_2 = { 4883ec20 488b1a 488d15e0ffffff 488bcb } // n = 4, score = 300 // 4883ec20 | inc edx // 488b1a | inc esp // 488d15e0ffffff | mov byte ptr [ebp + 0x6f], ch // 488bcb | inc esp $sequence_3 = { c705????????01000000 4883c420 5b 48ff25???????? } // n = 4, score = 300 // c705????????01000000 | // 4883c420 | dec esp // 5b | sub ecx, edi // 48ff25???????? | $sequence_4 = { 4883ec20 488b1a 488d15e0ffffff 488bcb ff15???????? 488905???????? 4885c0 } // n = 7, score = 300 // 4883ec20 | test eax, eax // 488b1a | je 0x871 // 488d15e0ffffff | dec eax // 488bcb | mov ecx, dword ptr [esp + 0x58] // ff15???????? | // 488905???????? | // 4885c0 | dec eax $sequence_5 = { 488bcb ff15???????? 488905???????? 4885c0 744a } // n = 5, score = 300 // 488bcb | xor ecx, ecx // ff15???????? | // 488905???????? | // 4885c0 | mov al, 5 // 744a | mov ecx, dword ptr [edi] $sequence_6 = { c705????????01000000 4883c420 5b 48ff25???????? 4883c420 } // n = 5, score = 300 // c705????????01000000 | // 4883c420 | dec eax // 5b | mov dword ptr [esp + 0x40], eax // 48ff25???????? | // 4883c420 | dec esp $sequence_7 = { 488d15e0ffffff 488bcb ff15???????? 488905???????? 4885c0 } // n = 5, score = 300 // 488d15e0ffffff | movzx eax, dx // 488bcb | lea edi, [edi - 0x18] // ff15???????? | // 488905???????? | // 4885c0 | lea edi, [eax + edi*2] $sequence_8 = { ff15???????? 85c0 742c 488bcb e8???????? 488b0d???????? } // n = 6, score = 300 // ff15???????? | // 85c0 | mov dword ptr [ebp], eax // 742c | dec eax // 488bcb | lea eax, [esp + 0x68] // e8???????? | // 488b0d???????? | $sequence_9 = { ff15???????? 85c0 742c 488bcb e8???????? } // n = 5, score = 300 // ff15???????? | // 85c0 | dec esp // 742c | lea eax, [0xbed0] // 488bcb | and edx, 0x3f // e8???????? | condition: 7 of them and filesize < 217088 }
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