SYMBOLCOMMON_NAMEaka. SYNONYMS
win.ufrstealer (Back to overview)

UFR Stealer

aka: Usteal

Information stealer.

References
2019-02-15Twitter (@malwrhunterteam)MalwareHunterTeam
@online{malwarehunterteam:20190215:malware:2512b91, author = {MalwareHunterTeam}, title = {{Tweet on Malware Sample}}, date = {2019-02-15}, organization = {Twitter (@malwrhunterteam)}, url = {https://twitter.com/malwrhunterteam/status/1096363455769202688}, language = {English}, urldate = {2019-11-29} } Tweet on Malware Sample
UFR Stealer
2017-09-15MicrosoftMicrosoft
@online{microsoft:20170915:trojanspywin32usteal:a2a860e, author = {Microsoft}, title = {{TrojanSpy:Win32/Usteal}}, date = {2017-09-15}, organization = {Microsoft}, url = {https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=TrojanSpy:Win32/Usteal}, language = {English}, urldate = {2020-01-08} } TrojanSpy:Win32/Usteal
UFR Stealer
Yara Rules
[TLP:WHITE] win_ufrstealer_auto (20220516 | Detects win.ufrstealer.)
rule win_ufrstealer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.ufrstealer."
        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.ufrstealer"
        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 = { 49 0fb631 3bd6 75f7 0fb67c0306 8bc8 2bca }
            // n = 7, score = 200
            //   49                   | dec                 ecx
            //   0fb631               | movzx               esi, byte ptr [ecx]
            //   3bd6                 | cmp                 edx, esi
            //   75f7                 | jne                 0xfffffff9
            //   0fb67c0306           | movzx               edi, byte ptr [ebx + eax + 6]
            //   8bc8                 | mov                 ecx, eax
            //   2bca                 | sub                 ecx, edx

        $sequence_1 = { 53 ff15???????? 85c0 0f8486030000 ff7508 6800010000 68???????? }
            // n = 7, score = 200
            //   53                   | push                ebx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   0f8486030000         | je                  0x38c
            //   ff7508               | push                dword ptr [ebp + 8]
            //   6800010000           | push                0x100
            //   68????????           |                     

        $sequence_2 = { 68???????? 68???????? ff15???????? 6800020000 68???????? 68???????? 68???????? }
            // n = 7, score = 200
            //   68????????           |                     
            //   68????????           |                     
            //   ff15????????         |                     
            //   6800020000           | push                0x200
            //   68????????           |                     
            //   68????????           |                     
            //   68????????           |                     

        $sequence_3 = { 8d8500f4ffff 50 ff15???????? 817c30fc44617461 0f8575010000 8b85ecf3ffff 8985e8f3ffff }
            // n = 7, score = 200
            //   8d8500f4ffff         | lea                 eax, [ebp - 0xc00]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   817c30fc44617461     | cmp                 dword ptr [eax + esi - 4], 0x61746144
            //   0f8575010000         | jne                 0x17b
            //   8b85ecf3ffff         | mov                 eax, dword ptr [ebp - 0xc14]
            //   8985e8f3ffff         | mov                 dword ptr [ebp - 0xc18], eax

        $sequence_4 = { 3bd6 75f7 0fb67c0306 8bc8 2bca 03cb 0fb671fe }
            // n = 7, score = 200
            //   3bd6                 | cmp                 edx, esi
            //   75f7                 | jne                 0xfffffff9
            //   0fb67c0306           | movzx               edi, byte ptr [ebx + eax + 6]
            //   8bc8                 | mov                 ecx, eax
            //   2bca                 | sub                 ecx, edx
            //   03cb                 | add                 ecx, ebx
            //   0fb671fe             | movzx               esi, byte ptr [ecx - 2]

        $sequence_5 = { 891d???????? ff35???????? 6a08 ff35???????? ff15???????? }
            // n = 5, score = 200
            //   891d????????         |                     
            //   ff35????????         |                     
            //   6a08                 | push                8
            //   ff35????????         |                     
            //   ff15????????         |                     

        $sequence_6 = { ff4df0 75ac c745f001000000 8b7df4 }
            // n = 4, score = 200
            //   ff4df0               | dec                 dword ptr [ebp - 0x10]
            //   75ac                 | jne                 0xffffffae
            //   c745f001000000       | mov                 dword ptr [ebp - 0x10], 1
            //   8b7df4               | mov                 edi, dword ptr [ebp - 0xc]

        $sequence_7 = { ff15???????? 8bc3 5b c9 c21400 55 }
            // n = 6, score = 200
            //   ff15????????         |                     
            //   8bc3                 | mov                 eax, ebx
            //   5b                   | pop                 ebx
            //   c9                   | leave               
            //   c21400               | ret                 0x14
            //   55                   | push                ebp

        $sequence_8 = { 68???????? e8???????? 8305????????02 6a02 68???????? e8???????? 8305????????02 }
            // n = 7, score = 200
            //   68????????           |                     
            //   e8????????           |                     
            //   8305????????02       |                     
            //   6a02                 | push                2
            //   68????????           |                     
            //   e8????????           |                     
            //   8305????????02       |                     

        $sequence_9 = { ff35???????? ff15???????? a3???????? 6800040000 }
            // n = 4, score = 200
            //   ff35????????         |                     
            //   ff15????????         |                     
            //   a3????????           |                     
            //   6800040000           | push                0x400

    condition:
        7 of them and filesize < 770048
}
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