Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 8438436edff4093e…

MALICIOUS

Office (OLE) / .XLSX

145.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: b8fcef887f90c9e32d076459b283c224 SHA-1: 24cf63ae90d9ebecb21ea1de99bfa797c3600ffe SHA-256: 8438436edff4093eecbca2e7b878c5740b3b7b24ff0a38b7e551c9060f84bb85
262 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample utilizes Excel 4.0 macros, specifically an Auto_Open function, to execute a series of concatenated strings that reconstruct URLs. These URLs are then used to download and execute a second-stage payload. The ClamAV detection and the nature of the macro indicate a downloader, consistent with Emotet's typical behavior. The reconstructed URLs include: "h"&"tt"&"p://lu"&"pu"&"s.ktcatl.com/w"&"p-co"&"nt"&"e"&"n"&"t/uC"&"cc"&"W"&"J/", "h"&"tt"&"ps:/"&"/pa"&"cke"&"rsan"&"dm"&"ov"&"er"&"sba"&"ng"&"al"&"orech"&"arges.c"&"o"&"m/c"&"g"&"i-b"&"i"&"n/Ur"&"I6GM"&"87K5u"&"2y2p"&"OW/", "h"&"tt"&"p:/

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 (5 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: Doc.Downloader.EmotetRed02222-9938635-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetRed02222-9938635-0
  • 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://lupus.ktcatl.com/wp-content/uCccWJ/
    • https://packersandmoversbangalorecharges.com/cgi-bin/UrI6GM87K5u2y2pOW/
    • http://123breathe.org/error/Drs/
    • https://greenesqualityflooring.com/error/kUO7NnkpMp2cs/
    • http://new.hssus.org/wp-includes/blocks/eKID0QAfLUS/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
1574ee13450fd34682012e2ebea7c020d326605272204fb688e7873d4a7c8165		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6756 bytes

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