SYMBOLCOMMON_NAMEaka. SYNONYMS
win.xorist (Back to overview)

Xorist


There is no description at this point.

References
2022-11-10FortinetShunichi Imano, James Slaughter
@online{imano:20221110:ransomware:f3245bf, author = {Shunichi Imano and James Slaughter}, title = {{Ransomware Roundup: New Inlock and Xorist Variants}}, date = {2022-11-10}, organization = {Fortinet}, url = {https://www.fortinet.com/blog/threat-research/Ransomware-Roundup-New-Inlock-and-Xorist-Variants}, language = {English}, urldate = {2022-11-21} } Ransomware Roundup: New Inlock and Xorist Variants
Inlock Xorist
Yara Rules
[TLP:WHITE] win_xorist_auto (20230407 | Detects win.xorist.)
rule win_xorist_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        version = "1"
        description = "Detects win.xorist."
        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.xorist"
        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 = { 7504 b001 eb44 53 e8???????? 6a0c 59 }
            // n = 7, score = 100
            //   7504                 | jne                 6
            //   b001                 | mov                 al, 1
            //   eb44                 | jmp                 0x46
            //   53                   | push                ebx
            //   e8????????           |                     
            //   6a0c                 | push                0xc
            //   59                   | pop                 ecx

        $sequence_1 = { ff742408 e8???????? 84c0 7404 b001 eb10 ff742404 }
            // n = 7, score = 100
            //   ff742408             | push                dword ptr [esp + 8]
            //   e8????????           |                     
            //   84c0                 | test                al, al
            //   7404                 | je                  6
            //   b001                 | mov                 al, 1
            //   eb10                 | jmp                 0x12
            //   ff742404             | push                dword ptr [esp + 4]

        $sequence_2 = { 56 e8???????? 59 8d8da8fbffff 8d3446 83c602 8bc6 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   8d8da8fbffff         | lea                 ecx, [ebp - 0x458]
            //   8d3446               | lea                 esi, [esi + eax*2]
            //   83c602               | add                 esi, 2
            //   8bc6                 | mov                 eax, esi

        $sequence_3 = { 8bcf 898668060000 e8???????? 89864c060000 898644060000 85c0 0f8432010000 }
            // n = 7, score = 100
            //   8bcf                 | mov                 ecx, edi
            //   898668060000         | mov                 dword ptr [esi + 0x668], eax
            //   e8????????           |                     
            //   89864c060000         | mov                 dword ptr [esi + 0x64c], eax
            //   898644060000         | mov                 dword ptr [esi + 0x644], eax
            //   85c0                 | test                eax, eax
            //   0f8432010000         | je                  0x138

        $sequence_4 = { 33748500 33749d00 8b442420 8bc8 d1c6 89749d00 8b5c2410 }
            // n = 7, score = 100
            //   33748500             | xor                 esi, dword ptr [ebp + eax*4]
            //   33749d00             | xor                 esi, dword ptr [ebp + ebx*4]
            //   8b442420             | mov                 eax, dword ptr [esp + 0x20]
            //   8bc8                 | mov                 ecx, eax
            //   d1c6                 | rol                 esi, 1
            //   89749d00             | mov                 dword ptr [ebp + ebx*4], esi
            //   8b5c2410             | mov                 ebx, dword ptr [esp + 0x10]

        $sequence_5 = { c20400 56 8b742408 ba00000400 3bf2 7328 8b09 }
            // n = 7, score = 100
            //   c20400               | ret                 4
            //   56                   | push                esi
            //   8b742408             | mov                 esi, dword ptr [esp + 8]
            //   ba00000400           | mov                 edx, 0x40000
            //   3bf2                 | cmp                 esi, edx
            //   7328                 | jae                 0x2a
            //   8b09                 | mov                 ecx, dword ptr [ecx]

        $sequence_6 = { 807f2c00 7527 8d4730 c6472c01 50 8d4718 50 }
            // n = 7, score = 100
            //   807f2c00             | cmp                 byte ptr [edi + 0x2c], 0
            //   7527                 | jne                 0x29
            //   8d4730               | lea                 eax, [edi + 0x30]
            //   c6472c01             | mov                 byte ptr [edi + 0x2c], 1
            //   50                   | push                eax
            //   8d4718               | lea                 eax, [edi + 0x18]
            //   50                   | push                eax

        $sequence_7 = { e8???????? 8bc6 50 e8???????? 59 8db5aafbffff }
            // n = 6, score = 100
            //   e8????????           |                     
            //   8bc6                 | mov                 eax, esi
            //   50                   | push                eax
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   8db5aafbffff         | lea                 esi, [ebp - 0x456]

        $sequence_8 = { 3894306c060000 74f1 0fb64101 8b542414 03e8 8b5c241c 8d842424040000 }
            // n = 7, score = 100
            //   3894306c060000       | cmp                 byte ptr [eax + esi + 0x66c], dl
            //   74f1                 | je                  0xfffffff3
            //   0fb64101             | movzx               eax, byte ptr [ecx + 1]
            //   8b542414             | mov                 edx, dword ptr [esp + 0x14]
            //   03e8                 | add                 ebp, eax
            //   8b5c241c             | mov                 ebx, dword ptr [esp + 0x1c]
            //   8d842424040000       | lea                 eax, [esp + 0x424]

        $sequence_9 = { 8b4c2428 83c40c 83c108 83c508 83eb08 894c241c 83ef01 }
            // n = 7, score = 100
            //   8b4c2428             | mov                 ecx, dword ptr [esp + 0x28]
            //   83c40c               | add                 esp, 0xc
            //   83c108               | add                 ecx, 8
            //   83c508               | add                 ebp, 8
            //   83eb08               | sub                 ebx, 8
            //   894c241c             | mov                 dword ptr [esp + 0x1c], ecx
            //   83ef01               | sub                 edi, 1

    condition:
        7 of them and filesize < 1402880
}
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