Unit 42 observed threat actor Tropical Scorpius using this RAT in operations where also Cuba ransomware was deployed.
rule win_romcom_rat_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.romcom_rat." 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.romcom_rat" 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 = { 33d2 448d4240 488d8d60100000 e8???????? 488d0d9a6e0100 e8???????? 4c8bc0 } // n = 7, score = 100 // 33d2 | dec esp // 448d4240 | mov eax, eax // 488d8d60100000 | lea esi, [edi + 1] // e8???????? | // 488d0d9a6e0100 | dec eax // e8???????? | // 4c8bc0 | sub ecx, esi $sequence_1 = { 488945a0 488d0592d20400 4885db 7424 83630800 488903 } // n = 6, score = 100 // 488945a0 | mov dword ptr [esp + 0x40], 0x4f004e // 488d0592d20400 | mov dword ptr [esp + 0x30], 0xc // 4885db | inc ecx // 7424 | mov ebx, 0x32 // 83630800 | mov dword ptr [esp + 0x34], 0x31383b32 // 488903 | mov dword ptr [esp + 0x38], 0x3a363837 $sequence_2 = { c7442434323b3831 c74424383738363a c744243c02005b00 c74424407e006900 c744244461005d00 c74424485e005200 c744244c52005400 } // n = 7, score = 100 // c7442434323b3831 | inc ecx // c74424383738363a | lea edx, [ecx + 0x1b] // c744243c02005b00 | inc ecx // c74424407e006900 | lea ecx, [ebp - 0x1000] // c744244461005d00 | dec esp // c74424485e005200 | mov dword ptr [esp + 0x30], edi // c744244c52005400 | test edi, edi $sequence_3 = { f30f7f458f 482bf3 4889742420 4c8d458f 488d55a7 498bce e8???????? } // n = 7, score = 100 // f30f7f458f | dec eax // 482bf3 | mov ecx, ebx // 4889742420 | nop // 4c8d458f | dec eax // 488d55a7 | lea eax, [0x40098] // 498bce | dec eax // e8???????? | $sequence_4 = { 488d8a50000000 e9???????? 4055 4883ec20 488bea 8b8598000000 83e002 } // n = 7, score = 100 // 488d8a50000000 | mov ebp, edx // e9???????? | // 4055 | mov edx, 0x458 // 4883ec20 | dec eax // 488bea | mov ecx, dword ptr [ebp + 0x78] // 8b8598000000 | ret // 83e002 | inc esp $sequence_5 = { eb24 488d152e6b0600 488d4b02 483bce 7714 41803c1f30 750d } // n = 7, score = 100 // eb24 | add ecx, esi // 488d152e6b0600 | inc esp // 488d4b02 | lea esp, [esi + 1] // 483bce | mov ecx, 0x202 // 7714 | mov dword ptr [ebp + 0xf40], 0x10 // 41803c1f30 | dec eax // 750d | lea edx, [ebp + 0xf70] $sequence_6 = { c7442460474e595a c7442464080a5d0d c74424685b5a4659 c744246c10475f51 c7442470141e5e19 c74424744b4b5f4f c744247848262600 } // n = 7, score = 100 // c7442460474e595a | test eax, eax // c7442464080a5d0d | jne 0x97 // c74424685b5a4659 | and dword ptr [esp + 0x3c], eax // c744246c10475f51 | inc ecx // c7442470141e5e19 | mov ecx, 0x41 // c74424744b4b5f4f | dec esp // c744247848262600 | lea eax, [ebp + 0x1060] $sequence_7 = { 498bd6 498bcd ff5038 498b4740 488b4808 48894d97 488b01 } // n = 7, score = 100 // 498bd6 | mov ecx, esi // 498bcd | dec eax // ff5038 | mov ecx, esi // 498b4740 | jmp 0x102c // 488b4808 | xor ecx, ecx // 48894d97 | dec eax // 488b01 | mov dword ptr [eax], ecx $sequence_8 = { ebd7 488d053e4d0300 ba80000000 0f1000 410f1106 0f104810 410f114e10 } // n = 7, score = 100 // ebd7 | xor cl, dl // 488d053e4d0300 | dec eax // ba80000000 | cmp ecx, edx // 0f1000 | jae 0x1979 // 410f1106 | dec eax // 0f104810 | lea eax, [ecx + 1] // 410f114e10 | dec eax $sequence_9 = { 894c2420 ff15???????? eb0c 48630d???????? e8???????? } // n = 5, score = 100 // 894c2420 | lea ecx, [0x1ca36] // ff15???????? | // eb0c | dec ebp // 48630d???????? | // e8???????? | condition: 7 of them and filesize < 1211392 }
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