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

Static analysis result for SHA-256 084af3708e5f8443…

MALICIOUS

Office (OOXML) / .XLSX

1.12 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-05-11
MD5: 19373f588f7b55362cf2b82c74496db6 SHA-1: ec97a67aa401ada130b4cee30a3191eb7b326ba5 SHA-256: 084af3708e5f84433cbcfe640f635222f2c01988d67196b936604ef37fe53c32
140 Risk Score

Malware Insights

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

The critical heuristic 'XLM payload reassembled from CHAR()/split formulas' indicates the presence of Excel 4.0 macros. These macros are designed to execute commands such as 'regsvr32' and download payloads from URLs starting with 'https://'. This suggests a downloader or initial access mechanism for further malicious activity.

Heuristics 3

  • Excel 4.0 macro sheet (3 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • XLM payload reassembled from CHAR()/split formulas critical OOXML_XLM_REASSEMBLED_PAYLOAD
    An Excel 4.0 macro sheet builds its payload inside the formula token stream by concatenating per-character CHAR() calls and string fragments, so no WinAPI name, shell command, or URL is ever contiguous in the .bin for a literal-bytes scan to find. Reassembling the formulas recovered download/execute API names, LOLBin commands (regsvr32/rundll32/mshta/wmic/powershell), or a payload URL — the de-obfuscated download-and-run kill chain.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
65ff18c247a3e5afe8770ff3a79d969eea338677724d5cc9e1723a36f893b610		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 3099136 bytes
ooxml_oleobject_00_ole10native_00.bin
a6724425b761391a2288cdb0e402bdc8cf2de9a4e93260c95af92b78344a367e		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 3072068 bytes
ooxml_oleobject_01.bin
673d8d22e178fc19849cc06db68faeb8e8a1307cdd51ce7fdf580343bc142b7b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 3099136 bytes
emf_00.emf
3f0f6bb70f3d65dcc8d248d78ac320bcc22b1148ea5fdd2c1043065d03460133		 ooxml-emf OOXML EMF part: xl/media/image1.emf 6144552 bytes
xlm_sheet_00.bin
da2604c6aff8f745f1ecd341adf17f7a1c02aeda307c5fa8b173b2efa460ae33		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 1015 bytes
xlm_sheet_01.bin
4c72aff54b15876b182ea317dfe7f8cf5a56608af683416802ab1a7d14f7cc30		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 2932 bytes
xlm_sheet_02.bin
0ed4d479bbf468ea247076b7e577b410ee360a0de73f6a455de514d12c0f1ab1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.bin 1321 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.