rule win_stealbit_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        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 = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 6a73 668985eafcffff 58 6a75 668985ecfcffff 58 668985eefcffff }
            // n = 7, score = 300
            //   6a73                 | push                0x73
            //   668985eafcffff       | mov                 word ptr [ebp - 0x316], ax
            //   58                   | pop                 eax
            //   6a75                 | push                0x75
            //   668985ecfcffff       | mov                 word ptr [ebp - 0x314], ax
            //   58                   | pop                 eax
            //   668985eefcffff       | mov                 word ptr [ebp - 0x312], ax

        $sequence_1 = { 6a2e 668945ee 668975e4 66894de8 668975ea 58 }
            // n = 6, score = 300
            //   6a2e                 | push                0x2e
            //   668945ee             | mov                 word ptr [ebp - 0x12], ax
            //   668975e4             | mov                 word ptr [ebp - 0x1c], si
            //   66894de8             | mov                 word ptr [ebp - 0x18], cx
            //   668975ea             | mov                 word ptr [ebp - 0x16], si
            //   58                   | pop                 eax

        $sequence_2 = { 6683fe20 740a 6683fe2e 7506 8bd1 eb02 }
            // n = 6, score = 300
            //   6683fe20             | cmp                 si, 0x20
            //   740a                 | je                  0xc
            //   6683fe2e             | cmp                 si, 0x2e
            //   7506                 | jne                 8
            //   8bd1                 | mov                 edx, ecx
            //   eb02                 | jmp                 4

        $sequence_3 = { 6a70 668985f0fdffff 668995eefdffff 5a 6a6c 58 }
            // n = 6, score = 300
            //   6a70                 | push                0x70
            //   668985f0fdffff       | mov                 word ptr [ebp - 0x210], ax
            //   668995eefdffff       | mov                 word ptr [ebp - 0x212], dx
            //   5a                   | pop                 edx
            //   6a6c                 | push                0x6c
            //   58                   | pop                 eax

        $sequence_4 = { 8bc6 5e c3 6a25 e8???????? }
            // n = 5, score = 300
            //   8bc6                 | mov                 eax, esi
            //   5e                   | pop                 esi
            //   c3                   | ret                 
            //   6a25                 | push                0x25
            //   e8????????           |                     

        $sequence_5 = { 668945a8 58 6a6f 668945aa 58 6a73 59 }
            // n = 7, score = 300
            //   668945a8             | mov                 word ptr [ebp - 0x58], ax
            //   58                   | pop                 eax
            //   6a6f                 | push                0x6f
            //   668945aa             | mov                 word ptr [ebp - 0x56], ax
            //   58                   | pop                 eax
            //   6a73                 | push                0x73
            //   59                   | pop                 ecx

        $sequence_6 = { 8901 8bc1 c3 e8???????? 8901 c3 8bd1 }
            // n = 7, score = 300
            //   8901                 | mov                 dword ptr [ecx], eax
            //   8bc1                 | mov                 eax, ecx
            //   c3                   | ret                 
            //   e8????????           |                     
            //   8901                 | mov                 dword ptr [ecx], eax
            //   c3                   | ret                 
            //   8bd1                 | mov                 edx, ecx

        $sequence_7 = { 83e0f0 660f6f08 660f74c8 660fd7d1 d3ea d3e2 0fbcd2 }
            // n = 7, score = 300
            //   83e0f0               | and                 eax, 0xfffffff0
            //   660f6f08             | movdqa              xmm1, xmmword ptr [eax]
            //   660f74c8             | pcmpeqb             xmm1, xmm0
            //   660fd7d1             | pmovmskb            edx, xmm1
            //   d3ea                 | shr                 edx, cl
            //   d3e2                 | shl                 edx, cl
            //   0fbcd2               | bsf                 edx, edx

        $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 = { 0f850e020000 2bcf 69c9ff000000 8d8114faffff 2b450c 03f0 8d8114faffff }
            // n = 7, score = 300
            //   0f850e020000         | jne                 0x214
            //   2bcf                 | sub                 ecx, edi
            //   69c9ff000000         | imul                ecx, ecx, 0xff
            //   8d8114faffff         | lea                 eax, [ecx - 0x5ec]
            //   2b450c               | sub                 eax, dword ptr [ebp + 0xc]
            //   03f0                 | add                 esi, eax
            //   8d8114faffff         | lea                 eax, [ecx - 0x5ec]

    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
}