rule win_stealbit_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        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 = "20230328"
        malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d"
        malpedia_version = "20230407"
        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 = { e8???????? 8b0f e8???????? 8d7f38 83eb01 75e9 8b96b4020000 }
            // n = 7, score = 300
            //   e8????????           |                     
            //   8b0f                 | mov                 ecx, dword ptr [edi]
            //   e8????????           |                     
            //   8d7f38               | lea                 edi, [edi + 0x38]
            //   83eb01               | sub                 ebx, 1
            //   75e9                 | jne                 0xffffffeb
            //   8b96b4020000         | mov                 edx, dword ptr [esi + 0x2b4]

        $sequence_1 = { 85c0 0f8529ffffff 57 56 6a05 5a 8d4df4 }
            // n = 7, score = 300
            //   85c0                 | test                eax, eax
            //   0f8529ffffff         | jne                 0xffffff2f
            //   57                   | push                edi
            //   56                   | push                esi
            //   6a05                 | push                5
            //   5a                   | pop                 edx
            //   8d4df4               | lea                 ecx, [ebp - 0xc]

        $sequence_2 = { 8bcf e8???????? 85c0 0f8511010000 53 8d45ac 8bd6 }
            // n = 7, score = 300
            //   8bcf                 | mov                 ecx, edi
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   0f8511010000         | jne                 0x117
            //   53                   | push                ebx
            //   8d45ac               | lea                 eax, [ebp - 0x54]
            //   8bd6                 | mov                 edx, esi

        $sequence_3 = { 5a 8bce e8???????? 85c0 740c f0ff8eac020000 e9???????? }
            // n = 7, score = 300
            //   5a                   | pop                 edx
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   740c                 | je                  0xe
            //   f0ff8eac020000       | lock dec            dword ptr [esi + 0x2ac]
            //   e9????????           |                     

        $sequence_4 = { eb03 8b4618 5e c9 c3 55 8bec }
            // n = 7, score = 300
            //   eb03                 | jmp                 5
            //   8b4618               | mov                 eax, dword ptr [esi + 0x18]
            //   5e                   | pop                 esi
            //   c9                   | leave               
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp

        $sequence_5 = { 668985befeffff 6a65 58 6a63 668985c0feffff 58 6a79 }
            // n = 7, score = 300
            //   668985befeffff       | mov                 word ptr [ebp - 0x142], ax
            //   6a65                 | push                0x65
            //   58                   | pop                 eax
            //   6a63                 | push                0x63
            //   668985c0feffff       | mov                 word ptr [ebp - 0x140], ax
            //   58                   | pop                 eax
            //   6a79                 | push                0x79

        $sequence_6 = { 884106 e8???????? 6a04 6a49 884107 e8???????? }
            // n = 6, score = 300
            //   884106               | mov                 byte ptr [ecx + 6], al
            //   e8????????           |                     
            //   6a04                 | push                4
            //   6a49                 | push                0x49
            //   884107               | mov                 byte ptr [ecx + 7], al
            //   e8????????           |                     

        $sequence_7 = { 0f85f4010000 6a0c 8d85a0feffff 8bd6 50 8bcf e8???????? }
            // n = 7, score = 300
            //   0f85f4010000         | jne                 0x1fa
            //   6a0c                 | push                0xc
            //   8d85a0feffff         | lea                 eax, [ebp - 0x160]
            //   8bd6                 | mov                 edx, esi
            //   50                   | push                eax
            //   8bcf                 | mov                 ecx, edi
            //   e8????????           |                     

        $sequence_8 = { 50 8bcf e8???????? 85c0 0f85e1000000 53 8d459c }
            // n = 7, score = 300
            //   50                   | push                eax
            //   8bcf                 | mov                 ecx, edi
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   0f85e1000000         | jne                 0xe7
            //   53                   | push                ebx
            //   8d459c               | lea                 eax, [ebp - 0x64]

        $sequence_9 = { 3bc1 7222 33d2 8b7d14 8bd9 f7f3 8bd0 }
            // n = 7, score = 300
            //   3bc1                 | cmp                 eax, ecx
            //   7222                 | jb                  0x24
            //   33d2                 | xor                 edx, edx
            //   8b7d14               | mov                 edi, dword ptr [ebp + 0x14]
            //   8bd9                 | mov                 ebx, ecx
            //   f7f3                 | div                 ebx
            //   8bd0                 | mov                 edx, eax

    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
}