Ransomware
rule win_sfile_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.sfile." 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.sfile" 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 = { c705????????00000000 833d????????00 7534 6850010000 6a40 } // n = 5, score = 300 // c705????????00000000 | // 833d????????00 | // 7534 | jne 0x36 // 6850010000 | push 0x150 // 6a40 | push 0x40 $sequence_1 = { 55 8bec 837d1000 7654 e8???????? 0fb6c0 } // n = 6, score = 300 // 55 | push ebp // 8bec | mov ebp, esp // 837d1000 | cmp dword ptr [ebp + 0x10], 0 // 7654 | jbe 0x56 // e8???????? | // 0fb6c0 | movzx eax, al $sequence_2 = { 3945f4 7d89 8b4dfc 034df4 c60100 837dec00 7547 } // n = 7, score = 300 // 3945f4 | cmp dword ptr [ebp - 0xc], eax // 7d89 | jge 0xffffff8b // 8b4dfc | mov ecx, dword ptr [ebp - 4] // 034df4 | add ecx, dword ptr [ebp - 0xc] // c60100 | mov byte ptr [ecx], 0 // 837dec00 | cmp dword ptr [ebp - 0x14], 0 // 7547 | jne 0x49 $sequence_3 = { 742d 6a00 8d55f8 52 6800010000 8b4518 } // n = 6, score = 300 // 742d | je 0x2f // 6a00 | push 0 // 8d55f8 | lea edx, [ebp - 8] // 52 | push edx // 6800010000 | push 0x100 // 8b4518 | mov eax, dword ptr [ebp + 0x18] $sequence_4 = { e8???????? 8945dc eb07 c745dc00000000 8b55f8 8b45dc } // n = 6, score = 300 // e8???????? | // 8945dc | mov dword ptr [ebp - 0x24], eax // eb07 | jmp 9 // c745dc00000000 | mov dword ptr [ebp - 0x24], 0 // 8b55f8 | mov edx, dword ptr [ebp - 8] // 8b45dc | mov eax, dword ptr [ebp - 0x24] $sequence_5 = { 8b5508 8b4220 83c001 8b4d08 894120 837dfc00 743a } // n = 7, score = 300 // 8b5508 | mov edx, dword ptr [ebp + 8] // 8b4220 | mov eax, dword ptr [edx + 0x20] // 83c001 | add eax, 1 // 8b4d08 | mov ecx, dword ptr [ebp + 8] // 894120 | mov dword ptr [ecx + 0x20], eax // 837dfc00 | cmp dword ptr [ebp - 4], 0 // 743a | je 0x3c $sequence_6 = { 8d95e4fdffff 52 8b4514 50 e8???????? 83c408 eb49 } // n = 7, score = 300 // 8d95e4fdffff | lea edx, [ebp - 0x21c] // 52 | push edx // 8b4514 | mov eax, dword ptr [ebp + 0x14] // 50 | push eax // e8???????? | // 83c408 | add esp, 8 // eb49 | jmp 0x4b $sequence_7 = { 51 e8???????? 83c408 eb13 8d95e4fdffff } // n = 5, score = 300 // 51 | push ecx // e8???????? | // 83c408 | add esp, 8 // eb13 | jmp 0x15 // 8d95e4fdffff | lea edx, [ebp - 0x21c] $sequence_8 = { b001 eb08 ebd5 32c0 eb02 b001 } // n = 6, score = 300 // b001 | mov al, 1 // eb08 | jmp 0xa // ebd5 | jmp 0xffffffd7 // 32c0 | xor al, al // eb02 | jmp 4 // b001 | mov al, 1 $sequence_9 = { 8955f4 8b45f4 50 6a40 } // n = 4, score = 300 // 8955f4 | mov dword ptr [ebp - 0xc], edx // 8b45f4 | mov eax, dword ptr [ebp - 0xc] // 50 | push eax // 6a40 | push 0x40 condition: 7 of them and filesize < 588800 }
If your designated proposal does not fit in any other category, feel free to write a free-text in the comment field below.
Please propose all changes regarding references on the Malpedia library page
Your suggestion will be reviewed before being published. Thank you for contributing!
YYYY-MM-DD
YYYY-MM
YYYY