Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 8742a7c49c440ed6…

MALICIOUS

Office (OLE) / .XLS

472.5 KB Created: 2021-12-17 13:23:39 Authoring application: Microsoft Excel@羀䶍Ǘ@똀ߒǗ
MD5: 750279c05a4fe34c3c8abf1b5893a24d SHA-1: cddef2e434bf9a2aff0aaadb36d94f5a0b3c85a9 SHA-256: 8742a7c49c440ed62bb185a9a62d4fd7c0f30de83b8f71dcca3f13a25d892b9e
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel 4.0 macro-enabled spreadsheet that uses an Auto_Open macro. It employs a common lure to trick users into enabling macros. The macro attempts to open a VBS file from a hardcoded path: "C:\ProgramData\DvBUMStPvzBuBeJC.vbs". While the extracted URLs were marked as benign, the presence of the Auto_Open macro and the attempt to execute a local script indicates malicious intent.

Heuristics 6

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • URL reconstructed from XLM cell array (3 URLs) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 https://cdn.discordapp.com/attachments/910256475912425536/921394603838562345/pdHfJDmerrynigga.bin
    • https://cdn.discordapp.com/attachments/910256475912425536/921395095591337985/NsmahQmerrynigga.bin
    • https://cdn.discordapp.com/attachments/910256475912425536/921395292098666516/uxUAiuwBnomerrynigga.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
22b14067f00cf8e6a2bea57257e8c543e0ea90536ab23e12ab0f1a89e6617532		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 215745 bytes

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