47 lines
1.8 KiB
Text
47 lines
1.8 KiB
Text
import "pe"
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rule MAL_DevilsTongue_HijackDll {
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meta:
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description = "Detects SOURGUM's DevilsTongue hijack DLL"
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author = "Microsoft Threat Intelligence Center (MSTIC)"
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date = "2021-07-15"
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reference = "https://www.microsoft.com/security/blog/2021/07/15/protecting-customers-from-a-private-sector-offensive-actor-using-0-day-exploits-and-devilstongue-malware/"
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score = 80
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id = "390b8b73-6740-513d-8c70-c9002be0ce69"
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strings:
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$str1 = "windows.old\\windows" wide
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$str2 = "NtQueryInformationThread"
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$str3 = "dbgHelp.dll" wide
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$str4 = "StackWalk64"
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$str5 = "ConvertSidToStringSidW"
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$str6 = "S-1-5-18" wide
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$str7 = "SMNew.dll" // DLL original name
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// Call check in stack manipulation
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// B8 FF 15 00 00 mov eax, 15FFh
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// 66 39 41 FA cmp [rcx-6], ax
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// 74 06 jz short loc_1800042B9
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// 80 79 FB E8 cmp byte ptr [rcx-5], 0E8h ;
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$code1 = { B8 FF 15 00 00 66 39 41 FA 74 06 80 79 FB E8 }
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// PRNG to generate number of times to sleep 1s before exiting
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// 44 8B C0 mov r8d, eax
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// B8 B5 81 4E 1B mov eax, 1B4E81B5h
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// 41 F7 E8 imul r8d
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// C1 FA 05 sar edx, 5
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// 8B CA mov ecx, edx
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// C1 E9 1F shr ecx, 1Fh
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// 03 D1 add edx, ecx
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// 69 CA 2C 01 00 00 imul ecx, edx, 12Ch
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// 44 2B C1 sub r8d, ecx
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// 45 85 C0 test r8d, r8d
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// 7E 19 jle short loc_1800014D0
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$code2 = { 44 8B C0 B8 B5 81 4E 1B 41 F7 E8 C1 FA 05 8B CA C1 E9 1F 03 D1 69 CA 2C 01 00 00 44 2B C1 45 85 C0 7E 19 }
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condition:
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filesize < 800KB and
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uint16(0) == 0x5A4D and
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( pe.characteristics & pe.DLL ) and
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(
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4 of them or
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( $code1 and $code2 ) or
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pe.imphash() == "9a964e810949704ff7b4a393d9adda60"
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)
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}
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