SYMBOLCOMMON_NAMEaka. SYNONYMS
win.mrdec (Back to overview)

MrDec


Ransomware.

References
2019-12-23Dissecting MalwareMarius Genheimer
@online{genheimer:20191223:i:516e8d0, author = {Marius Genheimer}, title = {{I literally can't think of a fitting pun - MrDec Ransomware}}, date = {2019-12-23}, organization = {Dissecting Malware}, url = {https://dissectingmalwa.re/i-literally-cant-think-of-a-fitting-pun-mrdec-ransomware.html}, language = {English}, urldate = {2020-03-27} } I literally can't think of a fitting pun - MrDec Ransomware
MrDec
Yara Rules
[TLP:WHITE] win_mrdec_auto (20220516 | Detects win.mrdec.)
rule win_mrdec_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.mrdec."
        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.mrdec"
        malpedia_rule_date = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 8b45e4 c1e005 0345ec 83780c01 }
            // n = 4, score = 100
            //   8b45e4               | mov                 eax, dword ptr [ebp - 0x1c]
            //   c1e005               | shl                 eax, 5
            //   0345ec               | add                 eax, dword ptr [ebp - 0x14]
            //   83780c01             | cmp                 dword ptr [eax + 0xc], 1

        $sequence_1 = { 8d45f8 50 6800010000 8d85e4feffff 50 ff75fc }
            // n = 6, score = 100
            //   8d45f8               | lea                 eax, [ebp - 8]
            //   50                   | push                eax
            //   6800010000           | push                0x100
            //   8d85e4feffff         | lea                 eax, [ebp - 0x11c]
            //   50                   | push                eax
            //   ff75fc               | push                dword ptr [ebp - 4]

        $sequence_2 = { ff75e4 e8???????? 6a00 ff75d8 e8???????? 68000000f0 6a01 }
            // n = 7, score = 100
            //   ff75e4               | push                dword ptr [ebp - 0x1c]
            //   e8????????           |                     
            //   6a00                 | push                0
            //   ff75d8               | push                dword ptr [ebp - 0x28]
            //   e8????????           |                     
            //   68000000f0           | push                0xf0000000
            //   6a01                 | push                1

        $sequence_3 = { e8???????? c64446fa00 57 56 e8???????? 68???????? 56 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   c64446fa00           | mov                 byte ptr [esi + eax*2 - 6], 0
            //   57                   | push                edi
            //   56                   | push                esi
            //   e8????????           |                     
            //   68????????           |                     
            //   56                   | push                esi

        $sequence_4 = { f3a4 0345fc c7005c2a2e2a c6400400 6860800100 e8???????? }
            // n = 6, score = 100
            //   f3a4                 | rep movsb           byte ptr es:[edi], byte ptr [esi]
            //   0345fc               | add                 eax, dword ptr [ebp - 4]
            //   c7005c2a2e2a         | mov                 dword ptr [eax], 0x2a2e2a5c
            //   c6400400             | mov                 byte ptr [eax + 4], 0
            //   6860800100           | push                0x18060
            //   e8????????           |                     

        $sequence_5 = { ff75dc 68???????? e8???????? 6a00 6a00 68???????? }
            // n = 6, score = 100
            //   ff75dc               | push                dword ptr [ebp - 0x24]
            //   68????????           |                     
            //   e8????????           |                     
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   68????????           |                     

        $sequence_6 = { fc f3a4 0345fc c7005c2a2e2a c6400400 6860800100 }
            // n = 6, score = 100
            //   fc                   | cld                 
            //   f3a4                 | rep movsb           byte ptr es:[edi], byte ptr [esi]
            //   0345fc               | add                 eax, dword ptr [ebp - 4]
            //   c7005c2a2e2a         | mov                 dword ptr [eax], 0x2a2e2a5c
            //   c6400400             | mov                 byte ptr [eax + 4], 0
            //   6860800100           | push                0x18060

        $sequence_7 = { ff75e0 e8???????? 3dea000000 752d ff75ec e8???????? }
            // n = 6, score = 100
            //   ff75e0               | push                dword ptr [ebp - 0x20]
            //   e8????????           |                     
            //   3dea000000           | cmp                 eax, 0xea
            //   752d                 | jne                 0x2f
            //   ff75ec               | push                dword ptr [ebp - 0x14]
            //   e8????????           |                     

        $sequence_8 = { 50 e8???????? 83f8ff 7526 8b4508 8bc8 }
            // n = 6, score = 100
            //   50                   | push                eax
            //   e8????????           |                     
            //   83f8ff               | cmp                 eax, -1
            //   7526                 | jne                 0x28
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   8bc8                 | mov                 ecx, eax

        $sequence_9 = { 68???????? e8???????? 85c0 0f84a4010000 }
            // n = 4, score = 100
            //   68????????           |                     
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   0f84a4010000         | je                  0x1aa

    condition:
        7 of them and filesize < 44864
}
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