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

Static analysis result for SHA-256 99fa8a389f11e739…

MALICIOUS

Office (OLE) / .XLS

31.0 KB Created: 2021-01-28 11:56:18 Authoring application: Microsoft Excel
MD5: d28593beddd91f5c50ea18cb338b67c7 SHA-1: 80e4964204ddbc5b60dcc71fabc058bfe289e765 SHA-256: 99fa8a389f11e7395e311a773bfe4239db6ad526f7f9c356a310dd17f8fa6a77
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample is an Excel 4.0 (XLM) macro-enabled spreadsheet. It contains an Auto_Open macro, which is a common technique for automatic execution upon opening the document. The document body explicitly instructs the user to 'Enable Editing' and 'Enable Content', indicating a lure to bypass security measures. The XLM macro uses dangerous formula APIs, including the RUN function, suggesting it attempts to execute arbitrary commands or download further payloads. No specific family could be identified, but the execution chain is clear.

Heuristics 4

  • 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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
5a6f9b306857b70e50510159d82660f24820f7bb3bcdd1724c387e33abcb1486
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3326 bytes