SYMBOLCOMMON_NAMEaka. SYNONYMS
win.dispenserxfs (Back to overview)

DispenserXFS


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References
2019-02-28Twitter (@cyb3rops)Florian Roth
@online{roth:20190228:yara:d1c9185, author = {Florian Roth}, title = {{Tweet on YARA and DispenserXFS}}, date = {2019-02-28}, organization = {Twitter (@cyb3rops)}, url = {https://twitter.com/cyb3rops/status/1101138784933085191}, language = {English}, urldate = {2020-01-10} } Tweet on YARA and DispenserXFS
DispenserXFS
Yara Rules
[TLP:WHITE] win_dispenserxfs_auto (20230125 | Detects win.dispenserxfs.)
rule win_dispenserxfs_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.dispenserxfs."
        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.dispenserxfs"
        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 = { 57 53 ff7514 e9???????? 68???????? }
            // n = 5, score = 200
            //   57                   | push                edi
            //   53                   | push                ebx
            //   ff7514               | push                dword ptr [ebp + 0x14]
            //   e9????????           |                     
            //   68????????           |                     

        $sequence_1 = { 8b8ddcfdffff 3bcf 7405 e8???????? }
            // n = 4, score = 200
            //   8b8ddcfdffff         | mov                 ecx, dword ptr [ebp - 0x224]
            //   3bcf                 | cmp                 ecx, edi
            //   7405                 | je                  7
            //   e8????????           |                     

        $sequence_2 = { c645ed00 50 ff7310 0fb703 ff7314 }
            // n = 5, score = 200
            //   c645ed00             | mov                 byte ptr [ebp - 0x13], 0
            //   50                   | push                eax
            //   ff7310               | push                dword ptr [ebx + 0x10]
            //   0fb703               | movzx               eax, word ptr [ebx]
            //   ff7314               | push                dword ptr [ebx + 0x14]

        $sequence_3 = { 57 8a06 84c0 7433 8bfe bb???????? 2bfb }
            // n = 7, score = 200
            //   57                   | push                edi
            //   8a06                 | mov                 al, byte ptr [esi]
            //   84c0                 | test                al, al
            //   7433                 | je                  0x35
            //   8bfe                 | mov                 edi, esi
            //   bb????????           |                     
            //   2bfb                 | sub                 edi, ebx

        $sequence_4 = { c645f92e c645fa64 c645fb6c c645fc6c c645fd00 8d45f4 50 }
            // n = 7, score = 200
            //   c645f92e             | mov                 byte ptr [ebp - 7], 0x2e
            //   c645fa64             | mov                 byte ptr [ebp - 6], 0x64
            //   c645fb6c             | mov                 byte ptr [ebp - 5], 0x6c
            //   c645fc6c             | mov                 byte ptr [ebp - 4], 0x6c
            //   c645fd00             | mov                 byte ptr [ebp - 3], 0
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   50                   | push                eax

        $sequence_5 = { 55 8bec 51 668b0d???????? 33c0 }
            // n = 5, score = 200
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   51                   | push                ecx
            //   668b0d????????       |                     
            //   33c0                 | xor                 eax, eax

        $sequence_6 = { 6800100000 53 ff75fc ffd0 }
            // n = 4, score = 200
            //   6800100000           | push                0x1000
            //   53                   | push                ebx
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ffd0                 | call                eax

        $sequence_7 = { 58 6689458a 33c0 66899d76ffffff }
            // n = 4, score = 200
            //   58                   | pop                 eax
            //   6689458a             | mov                 word ptr [ebp - 0x76], ax
            //   33c0                 | xor                 eax, eax
            //   66899d76ffffff       | mov                 word ptr [ebp - 0x8a], bx

        $sequence_8 = { 8b45f8 43 83c204 895df4 663bd8 0f8277ffffff 8b5dec }
            // n = 7, score = 200
            //   8b45f8               | mov                 eax, dword ptr [ebp - 8]
            //   43                   | inc                 ebx
            //   83c204               | add                 edx, 4
            //   895df4               | mov                 dword ptr [ebp - 0xc], ebx
            //   663bd8               | cmp                 bx, ax
            //   0f8277ffffff         | jb                  0xffffff7d
            //   8b5dec               | mov                 ebx, dword ptr [ebp - 0x14]

        $sequence_9 = { 8945da 8d45ec 50 53 8d45d4 }
            // n = 5, score = 200
            //   8945da               | mov                 dword ptr [ebp - 0x26], eax
            //   8d45ec               | lea                 eax, [ebp - 0x14]
            //   50                   | push                eax
            //   53                   | push                ebx
            //   8d45d4               | lea                 eax, [ebp - 0x2c]

    condition:
        7 of them and filesize < 114688
}
[TLP:WHITE] win_dispenserxfs_w0   (20190307 | Detects ATM Malware DispenserXFS)
import "pe"

rule win_dispenserxfs_w0 {
    meta:
        description = "Detects ATM Malware DispenserXFS"
        author = "@Xylit0l @r3c0nst / Modified by Florian Roth"
        reference = "https://twitter.com/r3c0nst/status/1100775857306652673"
        date = "2019/02/27"
        score = 80
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.dispenserxfs"
        malpedia_version = "20190307"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

    strings:
        $xc1 = { 68 FF FF 00 00 68 60 EA 00 00 6A 10 }
        $s1 = "\\dispenserXFS.pdb" ascii wide
        $s3 = "C:\\xfsasdf.txt" fullword ascii
        $s4 = "Injected mxsfs killer into %d." fullword ascii
        $s5 = "Waiting for freeze msxfs processes..." fullword ascii

    condition:
        1 of them or pe.imphash() == "617e037ae26d1931818db0790fb44bfe"
}
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