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

Static analysis result for SHA-256 992e89a8f2e16888…

MALICIOUS

Office (OLE) / .XLS

238.5 KB Created: 2021-12-15 11:58:24 Authoring application: Microsoft Excel@࿲Ǘ@릀أǗ
MD5: c36871aa8636b0a2c031991b6d647e1b SHA-1: 57bfa8299671040d1651fa78a8b272651676523c SHA-256: 992e89a8f2e16888f9c6c66fcd7f4e1e31f1b363c874530f42e74c2b1fb3bfe4
222 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1566.001 Spearphishing Attachment T1059.001 PowerShell

The sample contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening. The macro uses the FOPEN function to attempt to open a file named 'C:\ProgramData\JnDCcklAXX.vbs', indicating a likely download and execution of a second-stage payload. The document body explicitly instructs the user to 'Enable Content', further supporting the lure aspect of the attack. The presence of multiple Discord CDN URLs suggests potential staging locations for the payload.

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/917376142825107519/920620829178466314/zROHdxKMAmm.bin
    • https://cdn.discordapp.com/attachments/917384896975093793/920619334429208606/ndpksrYIC.bin
    • https://cdn.discordapp.com/attachments/917376142825107519/920620845532065802/LuTUobn.bin
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/exif/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a3dc19c55218ac908ed4d072332d962436d6100afe8846a11f3dc4375c9d64e6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3801 bytes

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