Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a91aca1916b5d2cf…

MALICIOUS

Office (OLE) / .XLSX

126.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-28
MD5: 8aabd50556cf7b58dace3375c5a6bf11 SHA-1: 2ca30a5f1b41d96205e59965d3bb3b0b7c96e6ba SHA-256: a91aca1916b5d2cf574bbfea582fe7704908c93b0878beb8f8b51a6eb7bc7f72
262 Risk Score

Malware Insights

Emotet · confidence 95%

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

This Excel 4.0 macro-enabled workbook contains an Auto_Open macro that executes a series of reconstructed URLs. The macro uses the `regsvr32.exe` command to download and execute a second-stage payload from one of the listed URLs, such as "h"&"tt"&"p:/"&"/w"&"w"&"w.f"&"or"&"en"&"s"&"is"&"b"&"il"&"is"&"i"&"m.c"&"o"&"m/a"&"n"&"k"&"ar"&"a/bp"&"ls"&"m"&"Kf"&"a"&"KA"&"w"&"A"&"y"&"a"&"v"&"N"&"j/". This behavior is characteristic of the Emotet malware family, which often uses macro-laced documents for initial infection. The ClamAV detection further supports this attribution.

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 (6 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.
  • ClamAV: Xls.Downloader.Emotet-adc2d23d2dc26dd0-9950240-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-adc2d23d2dc26dd0-9950240-0
  • 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.
  • 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.forensisbilisim.com/ankara/bplsmKfaKAwAyavNj/
    • https://www.faitmaison.uk/wp-admin/BZMoK/
    • http://www.parapetyrs.cz/wp-content/uploads/UTnG7GKKkZf/
    • http://www.fahriefe.com.tr/yargitaykararlari/aVg/
    • http://www.drcno.sk/_sub/FcEgwPugDI7wr2/
    • https://www.whow.fr/wp-includes/aZo78JmHBoEmW6fVQ/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
baa385ee141091e506d4fc8952e60f349e2a144300202c59dbc3e03ea3f9b493		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6541 bytes

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