rule win_karma_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        version = "1"
        description = "Detects win.karma."
        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.karma"
        malpedia_rule_date = "20230705"
        malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41"
        malpedia_version = "20230715"
        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 = { ff742428 8b4c2430 e8???????? 8b35???????? 33d2 }
            // n = 5, score = 100
            //   ff742428             | push                dword ptr [esp + 0x28]
            //   8b4c2430             | mov                 ecx, dword ptr [esp + 0x30]
            //   e8????????           |                     
            //   8b35????????         |                     
            //   33d2                 | xor                 edx, edx

        $sequence_1 = { 7ce6 57 8bd7 8bce e8???????? }
            // n = 5, score = 100
            //   7ce6                 | jl                  0xffffffe8
            //   57                   | push                edi
            //   8bd7                 | mov                 edx, edi
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     

        $sequence_2 = { 0f1006 0f114318 e8???????? 5f }
            // n = 4, score = 100
            //   0f1006               | movups              xmm0, xmmword ptr [esi]
            //   0f114318             | movups              xmmword ptr [ebx + 0x18], xmm0
            //   e8????????           |                     
            //   5f                   | pop                 edi

        $sequence_3 = { d1f8 83e902 40 8d1400 0f1f00 0fb70411 8d4902 }
            // n = 7, score = 100
            //   d1f8                 | sar                 eax, 1
            //   83e902               | sub                 ecx, 2
            //   40                   | inc                 eax
            //   8d1400               | lea                 edx, [eax + eax]
            //   0f1f00               | nop                 dword ptr [eax]
            //   0fb70411             | movzx               eax, word ptr [ecx + edx]
            //   8d4902               | lea                 ecx, [ecx + 2]

        $sequence_4 = { 0f1f4000 40 6683bc45f4fdffff00 75f4 6a00 6a00 50 }
            // n = 7, score = 100
            //   0f1f4000             | nop                 dword ptr [eax]
            //   40                   | inc                 eax
            //   6683bc45f4fdffff00     | cmp    word ptr [ebp + eax*2 - 0x20c], 0
            //   75f4                 | jne                 0xfffffff6
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   50                   | push                eax

        $sequence_5 = { 56 57 8d7902 33f6 8bd7 0fb64a01 }
            // n = 6, score = 100
            //   56                   | push                esi
            //   57                   | push                edi
            //   8d7902               | lea                 edi, [ecx + 2]
            //   33f6                 | xor                 esi, esi
            //   8bd7                 | mov                 edx, edi
            //   0fb64a01             | movzx               ecx, byte ptr [edx + 1]

        $sequence_6 = { 0f8484010000 83c702 ebc5 33ff 6690 0fb78ffc434000 0fb79c3c68020000 }
            // n = 7, score = 100
            //   0f8484010000         | je                  0x18a
            //   83c702               | add                 edi, 2
            //   ebc5                 | jmp                 0xffffffc7
            //   33ff                 | xor                 edi, edi
            //   6690                 | nop                 
            //   0fb78ffc434000       | movzx               ecx, word ptr [edi + 0x4043fc]
            //   0fb79c3c68020000     | movzx               ebx, word ptr [esp + edi + 0x268]

        $sequence_7 = { 8d4c2448 2bc2 83e902 d1f8 40 8d1400 660f1f440000 }
            // n = 7, score = 100
            //   8d4c2448             | lea                 ecx, [esp + 0x48]
            //   2bc2                 | sub                 eax, edx
            //   83e902               | sub                 ecx, 2
            //   d1f8                 | sar                 eax, 1
            //   40                   | inc                 eax
            //   8d1400               | lea                 edx, [eax + eax]
            //   660f1f440000         | nop                 word ptr [eax + eax]

        $sequence_8 = { c1c80e 33c7 8b7b14 8903 8d0437 c1c007 314324 }
            // n = 7, score = 100
            //   c1c80e               | ror                 eax, 0xe
            //   33c7                 | xor                 eax, edi
            //   8b7b14               | mov                 edi, dword ptr [ebx + 0x14]
            //   8903                 | mov                 dword ptr [ebx], eax
            //   8d0437               | lea                 eax, [edi + esi]
            //   c1c007               | rol                 eax, 7
            //   314324               | xor                 dword ptr [ebx + 0x24], eax

        $sequence_9 = { 8bf3 8d41bf 83f819 8d5120 8d46bf }
            // n = 5, score = 100
            //   8bf3                 | mov                 esi, ebx
            //   8d41bf               | lea                 eax, [ecx - 0x41]
            //   83f819               | cmp                 eax, 0x19
            //   8d5120               | lea                 edx, [ecx + 0x20]
            //   8d46bf               | lea                 eax, [esi - 0x41]

    condition:
        7 of them and filesize < 49208
}

import "pe"

rule win_karma_w0 {
    meta:
        author = "Blackberry Threat Research Team"
        description = "Detects Karma Ransomware 2021"
        date = "2021-10"
        license = "This Yara rule is provided under the Apache License 2.0 (https://www.apache.org/licenses/LICENSE-2.0) and open to any user or organization, as long as you use it under this license and ensure originator credit in any derivative to The BlackBerry Research & Intelligence Team"
        source = "https://blogs.blackberry.com/en/2021/11/threat-thursday-karma-ransomware"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.karma"
        malpedia_rule_date = "20211108"
        malpedia_hash = ""
        malpedia_version = "20211108"
        malpedia_license = "Apache License 2.0"
        malpedia_sharing = "TLP:WHITE"
 
    strings:
        $s1 = "WW91ciBuZXR3b3JrIGhhcyBiZWVuIGJyZWFjaGVkIGJ5IEthcm1hIHJhbnNvbXdhcmUgZ3JvdXAu" ascii wide
        $x2 = "crypt32.dll" nocase
        $x3 = "KARMA" ascii wide
        $x4 = "Sleep" nocase                            

    condition:
        //PE File
        uint16(0) == 0x5a4d and
        //Base64 Karma Note
        all of ($s*) and
        //All Strings
        all of ($x*)
}