Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 6840c6aeb9c9cf65…

MALICIOUS

Office (OOXML) / .XLSM

50.6 KB Created: 2020-02-01 18:28:07 UTC Authoring application: Microsoft Excel 12.0000
MD5: 917f869242e1c01eb49908feb4ca7c26 SHA-1: 1843496e3fd1b84ba2bb288bcdedb16621a760db SHA-256: 6840c6aeb9c9cf65a73ff7e39b17318ab4f77f08b9078c4bc1c18ae29de964cd
442 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 Visual Basic

The sample is an XLSM file containing VBA macros, specifically an Auto_Open macro that utilizes CreateObject. It embeds an Equation Editor OLE object which is known to be vulnerable to CVE-2017-11882. The heuristic indicates that this exploit is used to execute a command that likely downloads and runs a second-stage payload via WScript.

Heuristics 11

  • CVE-2017-11882 — Equation Editor command stager critical CVE likely CVE_2017_11882_EQUATION_NATIVE_CMD
    Embedded Equation Editor OLE data contains an invalid Equation Native/MTEF stream with an embedded command stager. This is likely CVE-2017-11882 exploitation because the vulnerable Equation Editor component is reached and the malformed native stream directly carries process-launch bytes.
  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject3.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • Embedded Office object carries macros critical OFFICE_EMBEDDED_MACRO_OBJECT
    This document embeds a second Office file that itself contains a VBA macro project or an Excel 4.0 (XLM) macro sheet. Hiding a macro-bearing workbook or document inside another document — frequently under an obfuscated, non-standard part name — is a macro-smuggling technique that defeats scanners which only inspect the outer document's macro storage. No benign authoring workflow stages a hidden macro project this way.
  • ClamAV: Doc.Dropper.Detected-9977031-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Detected-9977031-0
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open 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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 9

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
dbba3a5b6cc3996b8cc634e54fd683f6b5ef56d8df68edc28f9a607ea8e1469b		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 23791 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
ooxml_oleobject_00.bin
dea16f07fdbd87b841415195e9278d6d407728b2c40c4b5bf742bbb0750cbde1		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 13312 bytes
ooxml_oleobject_00_ole10native_00.bin
4b47fa8f2a111c278ca209bb39497be7bce99db078a1428681791ca0f07e926a		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10Native 10290 bytes
ooxml_oleobject_01.bin
26d3209a44acecb6ea4dc79de343552e20184e70e8012ec49b3ae3cb7269d0a1		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 15872 bytes
ooxml_oleobject_01_ole10native_00.bin
6c4566b9d4a0f48503ffc4f97cf510f744cd81dc1186bcde2809f43dc4552ba5		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 13253 bytes
ooxml_oleobject_02.bin
f511c7cf1066799b9a091ba24563f15bef83a456d4ba8703f8564b49255e72d7		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject3.bin 5936 bytes
ooxml_oleobject_03.bin
c87e0054f1104a0ed8484b30d640ebd15ee6cd0ea52dc87fca28d21a1b250a85		 ooxml-ole-object OOXML embedded OLE part: xl/vbaProject.bin 47616 bytes
Detection
ClamAV: Doc.Dropper.Detected-9977031-0
Obfuscation or payload: unlikely
emf_00.emf
979dde2aed02f077c16ae53546c6df9eed40e8386d6db6fc36aee9f966d2cb82		 ooxml-emf OOXML EMF part: xl/media/image1.emf 4968 bytes
emf_01.emf
4d4d1e7b04c99dcb8e885915068ad6f74cc2333e91580cdae5ccaa00c427247f		 ooxml-emf OOXML EMF part: xl/media/image2.emf 1536 bytes

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