SYMBOLCOMMON_NAMEaka. SYNONYMS
win.casper (Back to overview)

Casper

Actor(s): SNOWGLOBE


ESET describes Casper as a well-developed reconnaissance tool, making extensive efforts to remain unseen on targeted machines. Of particular note are the specific strategies adopted against anti-malware software. Casper was used against Syrian targets in April 2014, which makes it the most recent malware from this group publicly known at this time.

References
2015-03-05ESET ResearchJoan Calvet
@online{calvet:20150305:casper:be062ed, author = {Joan Calvet}, title = {{Casper Malware: After Babar and Bunny, Another Espionage Cartoon}}, date = {2015-03-05}, organization = {ESET Research}, url = {https://www.welivesecurity.com/2015/03/05/casper-malware-babar-bunny-another-espionage-cartoon/}, language = {English}, urldate = {2019-11-14} } Casper Malware: After Babar and Bunny, Another Espionage Cartoon
Casper
Yara Rules
[TLP:WHITE] win_casper_auto (20201023 | autogenerated rule brought to you by yara-signator)
rule win_casper_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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.casper"
        malpedia_rule_date = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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 = { 83c020 e8???????? 8b4508 83c020 eb58 }
            // n = 5, score = 100
            //   83c020               | add                 eax, 0x20
            //   e8????????           |                     
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   83c020               | add                 eax, 0x20
            //   eb58                 | jmp                 0x5a

        $sequence_1 = { 57 e8???????? 6a40 8d45ac 53 50 895da8 }
            // n = 7, score = 100
            //   57                   | push                edi
            //   e8????????           |                     
            //   6a40                 | push                0x40
            //   8d45ac               | lea                 eax, [ebp - 0x54]
            //   53                   | push                ebx
            //   50                   | push                eax
            //   895da8               | mov                 dword ptr [ebp - 0x58], ebx

        $sequence_2 = { 33ff 68???????? 56 e8???????? 8bd8 59 }
            // n = 6, score = 100
            //   33ff                 | xor                 edi, edi
            //   68????????           |                     
            //   56                   | push                esi
            //   e8????????           |                     
            //   8bd8                 | mov                 ebx, eax
            //   59                   | pop                 ecx

        $sequence_3 = { e8???????? 8bf0 c70424???????? e8???????? 59 56 50 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   c70424????????       |                     
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   56                   | push                esi
            //   50                   | push                eax

        $sequence_4 = { e8???????? 85c0 74c6 8b7004 85f6 74bf }
            // n = 6, score = 100
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   74c6                 | je                  0xffffffc8
            //   8b7004               | mov                 esi, dword ptr [eax + 4]
            //   85f6                 | test                esi, esi
            //   74bf                 | je                  0xffffffc1

        $sequence_5 = { 8945fc 0fb607 c1e802 8a8040a14200 }
            // n = 4, score = 100
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   0fb607               | movzx               eax, byte ptr [edi]
            //   c1e802               | shr                 eax, 2
            //   8a8040a14200         | mov                 al, byte ptr [eax + 0x42a140]

        $sequence_6 = { 6bc930 8975e0 8db180944200 8975e4 eb2b }
            // n = 5, score = 100
            //   6bc930               | imul                ecx, ecx, 0x30
            //   8975e0               | mov                 dword ptr [ebp - 0x20], esi
            //   8db180944200         | lea                 esi, [ecx + 0x429480]
            //   8975e4               | mov                 dword ptr [ebp - 0x1c], esi
            //   eb2b                 | jmp                 0x2d

        $sequence_7 = { e8???????? a3???????? eb07 8325????????00 ff35???????? e8???????? a1???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   a3????????           |                     
            //   eb07                 | jmp                 9
            //   8325????????00       |                     
            //   ff35????????         |                     
            //   e8????????           |                     
            //   a1????????           |                     

        $sequence_8 = { 40 59 83f83c 762a 56 e8???????? 8d044584b04200 }
            // n = 7, score = 100
            //   40                   | inc                 eax
            //   59                   | pop                 ecx
            //   83f83c               | cmp                 eax, 0x3c
            //   762a                 | jbe                 0x2c
            //   56                   | push                esi
            //   e8????????           |                     
            //   8d044584b04200       | lea                 eax, [eax*2 + 0x42b084]

        $sequence_9 = { 56 ff7508 ff7508 ffd0 85c0 7513 33ff }
            // n = 7, score = 100
            //   56                   | push                esi
            //   ff7508               | push                dword ptr [ebp + 8]
            //   ff7508               | push                dword ptr [ebp + 8]
            //   ffd0                 | call                eax
            //   85c0                 | test                eax, eax
            //   7513                 | jne                 0x15
            //   33ff                 | xor                 edi, edi

    condition:
        7 of them and filesize < 434176
}
[TLP:WHITE] win_casper_w0   (20180301 | Casper French Espionage Malware - Win32/ProxyBot.B - x86 Payload http://goo.gl/VRJNLo)
rule win_casper_w0 {
	meta:
		author = "Florian Roth"
		description = "Casper French Espionage Malware - Win32/ProxyBot.B - x86 Payload http://goo.gl/VRJNLo"
		reference = "http://goo.gl/VRJNLo"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.casper"
        malpedia_version = "20180301"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
	strings:
		$s1 = "\"svchost.exe\"" fullword wide
		$s2 = "firefox.exe" fullword ascii
		$s3 = "\"Host Process for Windows Services\"" fullword wide
		
		$x1 = "\\Users\\*" fullword ascii
		$x2 = "\\Roaming\\Mozilla\\Firefox\\Profiles\\*" fullword ascii
		$x3 = "\\Mozilla\\Firefox\\Profiles\\*" fullword ascii
		$x4 = "\\Documents and Settings\\*" fullword ascii
		
		$y1 = "%s; %S=%S" fullword wide
		$y2 = "%s; %s=%s" fullword ascii
		$y3 = "Cookie: %s=%s" fullword ascii
		$y4 = "http://%S:%d" fullword wide
		
		$z1 = "http://google.com/" fullword ascii
		$z2 = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; MALC)" fullword ascii
		$z3 = "Operating System\"" fullword wide
	condition:
		( all of ($s*) ) or
		( 3 of ($x*) and 2 of ($y*) and 2 of ($z*) )
}
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