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

Static analysis result for SHA-256 ee84727646dbe5da…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-27 11:38:01 Authoring application: Microsoft Excel First seen: 2022-02-26
MD5: de900d919c9eea307cf392bf173f66b6 SHA-1: 24b0e0e7055ce860a1f209d9ce7adc1dfec65fbb SHA-256: ee84727646dbe5da844764980ca6bbc9cc60992973a6f68e641e6f66c19db8fb
140 Risk Score

Malware Insights

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

The sample is an Excel 4.0 (XLM) macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for automatic execution upon opening the document. The XLM macro sheet contains dangerous formula APIs, specifically the 'RUN' function, suggesting it is designed to execute arbitrary commands. The document body contains heavily obfuscated text, but the presence of the Auto_Open function and the use of dangerous XLM functions strongly indicate a malicious intent to download and execute a second-stage payload.

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
d06d71e722a3076b2c6896c36171d1bb4383c6eaf07d203490dfeab8afb47c8e
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6547 bytes