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

Static analysis result for SHA-256 61c9b739434090d4…

MALICIOUS

Office (OLE) / .XLS

44.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: bd6b14867cba1347253d25c2eb9103fb SHA-1: c731fa5d17113c9bd6e7d917b2802f2132ea913b SHA-256: 61c9b739434090d42ab9112e5d100857c0e05f0532791ca28f4a866657fe3937
282 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter T1566.001 Spearphishing Attachment

The sample contains Excel 4.0 macros (XLM) that are configured to auto-execute upon opening, indicated by the 'Auto_Open' defined name and the use of dangerous formula APIs like RUN. These macros leverage the URLDownloadToFile API to download a payload from the embedded URL http://www.nowemiasteczko.pl/cigpndrozhm/. The presence of a macro-enable lure further suggests an attempt to trick the user into executing the malicious content.

Heuristics 7

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • 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 (1 URL) 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 http://www.nowemiasteczko.pl/cigpndrozhm/
    • http://www.nowemiasteczko.pl/cigpndrozhm/�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
43e877448e4b62647c494af7dd44bbe190b308a8fbb14af3219e723fa7bdf951		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2891 bytes

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