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

Static analysis result for SHA-256 5db4870d9646dde7…

MALICIOUS

Office (OLE) / .XLS

235.0 KB Created: 2021-10-27 10:31:49 Authoring application: Microsoft Excel
MD5: 79c2034357c210a37826ac2e107ee1f2 SHA-1: 93e961e97e679dbe38bb6bafc0d58061fb9f907e SHA-256: 5db4870d9646dde76f182f741bebecd88eb5a027e0d11cc1859b0c0eedeb6582
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains Excel 4.0 macros, including an Auto_Open entry, which is a strong indicator of malicious intent. The macros are designed to execute a command that constructs and runs a URL, likely to download and execute a second-stage payload. The reconstructed path 'C:\ProgramData\MISeLjaBAtOEPJ.rtf' suggests a dropped file, and the embedded URLs point to potential download locations for this payload.

Heuristics 5

  • 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 (4 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.
  • 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://149.129.254.152:8080/6tfcnfucknugget4gpenis3dade5z6cpc
    • https://cdn.discordapp.com/attachments/911246617275957290/915526461379727370/GYRxsMXKtvwSwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526468073848872/xTpcaEZvwmHqwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526473467719720/KsXtuXmxoZvgudVwhoreniggagay.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
48b7ad97812f84476b2a34f9ba9e910a6b141300af789f06fe1bfdaaab7cbadb		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2089 bytes

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