rule win_stealc_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        version = "1"
        description = "Detects win.stealc."
        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.stealc"
        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 = { 7507 50 ff15???????? 8d45f4 50 8d45fc 50 }
            // n = 7, score = 400
            //   7507                 | jne                 9
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   50                   | push                eax
            //   8d45fc               | lea                 eax, [ebp - 4]
            //   50                   | push                eax

        $sequence_1 = { 83c468 e8???????? 8b45f4 e8???????? 33c0 e8???????? ff75f0 }
            // n = 7, score = 400
            //   83c468               | add                 esp, 0x68
            //   e8????????           |                     
            //   8b45f4               | mov                 eax, dword ptr [ebp - 0xc]
            //   e8????????           |                     
            //   33c0                 | xor                 eax, eax
            //   e8????????           |                     
            //   ff75f0               | push                dword ptr [ebp - 0x10]

        $sequence_2 = { e8???????? 8b7dfc ff35???????? 8b470c 50 ff15???????? }
            // n = 6, score = 400
            //   e8????????           |                     
            //   8b7dfc               | mov                 edi, dword ptr [ebp - 4]
            //   ff35????????         |                     
            //   8b470c               | mov                 eax, dword ptr [edi + 0xc]
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_3 = { ff75ac ff75fc ff15???????? 57 ff75fc ff15???????? ff7530 }
            // n = 7, score = 400
            //   ff75ac               | push                dword ptr [ebp - 0x54]
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff15????????         |                     
            //   57                   | push                edi
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff15????????         |                     
            //   ff7530               | push                dword ptr [ebp + 0x30]

        $sequence_4 = { f3aa 8bc6 e8???????? 53 }
            // n = 4, score = 400
            //   f3aa                 | rep stosb           byte ptr es:[edi], al
            //   8bc6                 | mov                 eax, esi
            //   e8????????           |                     
            //   53                   | push                ebx

        $sequence_5 = { 3bfb 0f8c9d000000 8b45fc 8d55f8 52 68???????? 895df8 }
            // n = 7, score = 400
            //   3bfb                 | cmp                 edi, ebx
            //   0f8c9d000000         | jl                  0xa3
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   8d55f8               | lea                 edx, [ebp - 8]
            //   52                   | push                edx
            //   68????????           |                     
            //   895df8               | mov                 dword ptr [ebp - 8], ebx

        $sequence_6 = { 83c40c 50 8d858cfeffff 50 ff15???????? }
            // n = 5, score = 400
            //   83c40c               | add                 esp, 0xc
            //   50                   | push                eax
            //   8d858cfeffff         | lea                 eax, [ebp - 0x174]
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_7 = { 59 8b45d4 e8???????? ff75f0 }
            // n = 4, score = 400
            //   59                   | pop                 ecx
            //   8b45d4               | mov                 eax, dword ptr [ebp - 0x2c]
            //   e8????????           |                     
            //   ff75f0               | push                dword ptr [ebp - 0x10]

        $sequence_8 = { 57 ff7508 8bf8 ff15???????? 034708 894608 40 }
            // n = 7, score = 400
            //   57                   | push                edi
            //   ff7508               | push                dword ptr [ebp + 8]
            //   8bf8                 | mov                 edi, eax
            //   ff15????????         |                     
            //   034708               | add                 eax, dword ptr [edi + 8]
            //   894608               | mov                 dword ptr [esi + 8], eax
            //   40                   | inc                 eax

        $sequence_9 = { a5 a5 83ec50 a5 8d5d10 8bfc }
            // n = 6, score = 400
            //   a5                   | movsd               dword ptr es:[edi], dword ptr [esi]
            //   a5                   | movsd               dword ptr es:[edi], dword ptr [esi]
            //   83ec50               | sub                 esp, 0x50
            //   a5                   | movsd               dword ptr es:[edi], dword ptr [esi]
            //   8d5d10               | lea                 ebx, [ebp + 0x10]
            //   8bfc                 | mov                 edi, esp

    condition:
        7 of them and filesize < 24891648
}

rule win_stealc_w0 {
   meta:
       malware = "Stealc"
       description = "Find standalone Stealc sample based on decryption routine or characteristic strings"
       source = "SEKOIA.IO"
       reference = "https://blog.sekoia.io/stealc-a-copycat-of-vidar-and-raccoon-infostealers-gaining-in-popularity-part-1/"
       classification = "TLP:CLEAR"
       hash = "77d6f1914af6caf909fa2a246fcec05f500f79dd56e5d0d466d55924695c702d"
       author = "crep1x"
       malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.stealc"
       malpedia_version = "20230221"
       malpedia_license = "CC BY-NC-SA 4.0"
       malpedia_sharing = "TLP:WHITE"
       malpedia_rule_date = "20230221"
       malpedia_hash = ""
   strings:
       $dec = { 55 8b ec 8b 4d ?? 83 ec 0c 56 57 e8 ?? ?? ?? ?? 6a 03 33 d2 8b f8 59 f7 f1 8b c7 85 d2 74 04 } //deobfuscation function

       $str01 = "------" ascii
       $str02 = "Network Info:" ascii
       $str03 = "- IP: IP?" ascii
       $str04 = "- Country: ISO?" ascii
       $str05 = "- Display Resolution:" ascii
       $str06 = "User Agents:" ascii
       $str07 = "%s\\%s\\%s" ascii

   condition:
       uint16(0) == 0x5A4D and ($dec or 5 of ($str*))
}