SYMBOLCOMMON_NAMEaka. SYNONYMS
win.knot (Back to overview)

Knot


Ransomware.

References
2021-01-02Twitter (MalwareHunterTeam)MalwareHunterTeam
@online{malwarehunterteam:20210102:knot:66922b6, author = {MalwareHunterTeam}, title = {{Tweet on Knot Ransomware}}, date = {2021-01-02}, organization = {Twitter (MalwareHunterTeam)}, url = {https://twitter.com/malwrhunterteam/status/1345313324825780226}, language = {English}, urldate = {2021-01-04} } Tweet on Knot Ransomware
Knot
Yara Rules
[TLP:WHITE] win_knot_auto (20230125 | Detects win.knot.)
rule win_knot_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.knot."
        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.knot"
        malpedia_rule_date = "20230124"
        malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686"
        malpedia_version = "20230125"
        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 = { e8???????? 83c404 6808020000 8d95f0fdffff }
            // n = 4, score = 200
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   6808020000           | push                0x208
            //   8d95f0fdffff         | lea                 edx, [ebp - 0x210]

        $sequence_1 = { 83c404 68???????? ff15???????? e9???????? 8d95f4fdffff 52 }
            // n = 6, score = 200
            //   83c404               | add                 esp, 4
            //   68????????           |                     
            //   ff15????????         |                     
            //   e9????????           |                     
            //   8d95f4fdffff         | lea                 edx, [ebp - 0x20c]
            //   52                   | push                edx

        $sequence_2 = { 8d85a0fbffff 50 68???????? ff15???????? 89858cf9ffff 83bd8cf9ffffff }
            // n = 6, score = 200
            //   8d85a0fbffff         | lea                 eax, [ebp - 0x460]
            //   50                   | push                eax
            //   68????????           |                     
            //   ff15????????         |                     
            //   89858cf9ffff         | mov                 dword ptr [ebp - 0x674], eax
            //   83bd8cf9ffffff       | cmp                 dword ptr [ebp - 0x674], -1

        $sequence_3 = { 51 ff15???????? 8d95d8feffff 52 8b85d4feffff }
            // n = 5, score = 200
            //   51                   | push                ecx
            //   ff15????????         |                     
            //   8d95d8feffff         | lea                 edx, [ebp - 0x128]
            //   52                   | push                edx
            //   8b85d4feffff         | mov                 eax, dword ptr [ebp - 0x12c]

        $sequence_4 = { 6a04 8b45ec 50 ff15???????? 8945fc 837dfc00 }
            // n = 6, score = 200
            //   6a04                 | push                4
            //   8b45ec               | mov                 eax, dword ptr [ebp - 0x14]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   837dfc00             | cmp                 dword ptr [ebp - 4], 0

        $sequence_5 = { 51 6a08 8d95c8fdffff 52 8b45f0 50 ff15???????? }
            // n = 7, score = 200
            //   51                   | push                ecx
            //   6a08                 | push                8
            //   8d95c8fdffff         | lea                 edx, [ebp - 0x238]
            //   52                   | push                edx
            //   8b45f0               | mov                 eax, dword ptr [ebp - 0x10]
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_6 = { 6a01 8b4df4 51 ff15???????? 85c0 7507 32c0 }
            // n = 7, score = 200
            //   6a01                 | push                1
            //   8b4df4               | mov                 ecx, dword ptr [ebp - 0xc]
            //   51                   | push                ecx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7507                 | jne                 9
            //   32c0                 | xor                 al, al

        $sequence_7 = { 8d8d90f9ffff 51 e8???????? 83c408 8d9580f7ffff }
            // n = 5, score = 200
            //   8d8d90f9ffff         | lea                 ecx, [ebp - 0x670]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8d9580f7ffff         | lea                 edx, [ebp - 0x880]

        $sequence_8 = { 85c0 7507 32c0 e9???????? c785d8fdffff00000000 8d85d8fdffff }
            // n = 6, score = 200
            //   85c0                 | test                eax, eax
            //   7507                 | jne                 9
            //   32c0                 | xor                 al, al
            //   e9????????           |                     
            //   c785d8fdffff00000000     | mov    dword ptr [ebp - 0x228], 0
            //   8d85d8fdffff         | lea                 eax, [ebp - 0x228]

        $sequence_9 = { 51 ff15???????? 85c0 0f840e020000 6880000000 8d9580f7ffff }
            // n = 6, score = 200
            //   51                   | push                ecx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   0f840e020000         | je                  0x214
            //   6880000000           | push                0x80
            //   8d9580f7ffff         | lea                 edx, [ebp - 0x880]

    condition:
        7 of them and filesize < 59392
}
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