This is a stealer used by LockBit 2.0.
rule win_stealbit_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.stealbit." 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.stealbit" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" 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 = { 8b4e30 e8???????? 8b4e30 e8???????? 83663000 8d562c } // n = 6, score = 300 // 8b4e30 | mov ecx, dword ptr [esi + 0x30] // e8???????? | // 8b4e30 | mov ecx, dword ptr [esi + 0x30] // e8???????? | // 83663000 | and dword ptr [esi + 0x30], 0 // 8d562c | lea edx, [esi + 0x2c] $sequence_1 = { 8d8580fbffff 50 e8???????? 8bc8 e8???????? ffd0 8bd8 } // n = 7, score = 300 // 8d8580fbffff | lea eax, [ebp - 0x480] // 50 | push eax // e8???????? | // 8bc8 | mov ecx, eax // e8???????? | // ffd0 | call eax // 8bd8 | mov ebx, eax $sequence_2 = { 8bfa 8bd9 e8???????? 8bc8 e8???????? ffd0 8bf0 } // n = 7, score = 300 // 8bfa | mov edi, edx // 8bd9 | mov ebx, ecx // e8???????? | // 8bc8 | mov ecx, eax // e8???????? | // ffd0 | call eax // 8bf0 | mov esi, eax $sequence_3 = { e8???????? 8bc8 e8???????? ffd0 6a02 68bf000000 53 } // n = 7, score = 300 // e8???????? | // 8bc8 | mov ecx, eax // e8???????? | // ffd0 | call eax // 6a02 | push 2 // 68bf000000 | push 0xbf // 53 | push ebx $sequence_4 = { c786a802000000000000 8d7e50 33db 8b4620 } // n = 4, score = 300 // c786a802000000000000 | mov dword ptr [esi + 0x2a8], 0 // 8d7e50 | lea edi, [esi + 0x50] // 33db | xor ebx, ebx // 8b4620 | mov eax, dword ptr [esi + 0x20] $sequence_5 = { 6a6f 66898546ffffff 33c0 66898548ffffff 58 6a63 668985d2fcffff } // n = 7, score = 300 // 6a6f | push 0x6f // 66898546ffffff | mov word ptr [ebp - 0xba], ax // 33c0 | xor eax, eax // 66898548ffffff | mov word ptr [ebp - 0xb8], ax // 58 | pop eax // 6a63 | push 0x63 // 668985d2fcffff | mov word ptr [ebp - 0x32e], ax $sequence_6 = { 66899570feffff 66899574feffff 5a 6a6d 58 6a69 66898500feffff } // n = 7, score = 300 // 66899570feffff | mov word ptr [ebp - 0x190], dx // 66899574feffff | mov word ptr [ebp - 0x18c], dx // 5a | pop edx // 6a6d | push 0x6d // 58 | pop eax // 6a69 | push 0x69 // 66898500feffff | mov word ptr [ebp - 0x200], ax $sequence_7 = { 6689859afeffff 33c0 668955de 5a 6a61 6689bd86feffff } // n = 6, score = 300 // 6689859afeffff | mov word ptr [ebp - 0x166], ax // 33c0 | xor eax, eax // 668955de | mov word ptr [ebp - 0x22], dx // 5a | pop edx // 6a61 | push 0x61 // 6689bd86feffff | mov word ptr [ebp - 0x17a], di $sequence_8 = { 8945f8 e8???????? 03c0 8bce 8bd0 e8???????? 6a0c } // n = 7, score = 300 // 8945f8 | mov dword ptr [ebp - 8], eax // e8???????? | // 03c0 | add eax, eax // 8bce | mov ecx, esi // 8bd0 | mov edx, eax // e8???????? | // 6a0c | push 0xc $sequence_9 = { e8???????? 8bc8 e8???????? 3d15cffdb1 740b 46 3bf7 } // n = 7, score = 300 // e8???????? | // 8bc8 | mov ecx, eax // e8???????? | // 3d15cffdb1 | cmp eax, 0xb1fdcf15 // 740b | je 0xd // 46 | inc esi // 3bf7 | cmp esi, edi condition: 7 of them and filesize < 131072 }
rule win_stealbit_w0 { meta: description = "Detects Stealbit used by Lockbit 2.0 Ransomware Gang" author = "Frank Boldewin (@r3c0nst)" reference = "https://raw.githubusercontent.com/fboldewin/YARA-rules/master/Lockbit2.Stealbit.yar" date = "2021-08-12" hash1 = "3407f26b3d69f1dfce76782fee1256274cf92f744c65aa1ff2d3eaaaf61b0b1d" hash2 = "bd14872dd9fdead89fc074fdc5832caea4ceac02983ec41f814278130b3f943e" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.stealbit" malpedia_rule_date = "20210818" malpedia_hash = "" malpedia_version = "20210818" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" strings: $C2Decryption = {33 C9 8B C1 83 E0 0F 8A 80 ?? ?? ?? ?? 30 81 ?? ?? ?? ?? 41 83 F9 7C 72 E9 E8} condition: uint16(0) == 0x5A4D and filesize < 100KB and $C2Decryption }
If your designated proposal does not fit in any other category, feel free to write a free-text in the comment field below. Changes regarding references should be proposed on the Malpedia library page.
Your suggestion will be reviewed before being published. Thank you for contributing!
YYYY-MM-DD
YYYY-MM
YYYY