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

Static analysis result for SHA-256 18583539371bd938…

MALICIOUS

Office (OLE) / .XLS

46.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-09
MD5: 691674ecf0c0f826fe3a9b947300b21b SHA-1: 109d4c5e69e2e5641bfc5eed9b764aaad6d52022 SHA-256: 18583539371bd938b6f76f719da49b75d9c5f9b5829698d1b738d24e22efa1f4
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros with an Auto_Open entry, indicating automatic execution upon opening. The macros construct several URLs by concatenating strings, such as 'http://wps://w"&"pb"&"izw"&"o"&"n.c"&"o"&"m/F"&"ex"&"OL"&"2W"&"x0"&"0o"&"oC"&"fp"&"gO"&"w/', which are likely used to download and execute a secondary malicious payload. The use of Auto_Open and concatenated URLs points to a macro-based downloader, commonly delivered via spearphishing attachments.

Heuristics 3

  • 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.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
8530ce57f2115827ea23c5c95d01d856452a8f9ec319f9a971de39914dabeda2		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7802 bytes

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