Office (OLE) / .XLSX malware analysis — malicious · d4cb1ac74b40b8d6

MALICIOUS

Office (OLE) / .XLSX

830.0 KB Created: 2020-03-23 14:19:10 Authoring application: Microsoft Excel First seen: 2023-02-20

MD5: 8928d53735102e8e91d8181607ba26da SHA-1: 93976e2963445cd42272b7b044bc581cecdaa9d7 SHA-256: d4cb1ac74b40b8d6de535b009efc51606f432ede2ade75145eed4fdd921f79b7

282 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell T1059.004 JScript/VBScript

The sample contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The macro sheet includes references to dangerous functions like RUN and environment evasion checks, indicating an attempt to download and execute a payload from the URL http://0b.htb/s.dll. The presence of ShellExecute and URLDownloadToFile APIs further supports this malicious intent.

Heuristics 7

Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD

Reference to URLDownloadToFile API
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.
Reference to ShellExecute API high SC_STR_SHELLEXEC

Reference to ShellExecute API
XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT

Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
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://0b.htb/s.dll�

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `a8770f019793b6e706ca3f4c1f5502c43e46243f69ef72f9407612d4d447dac8`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	2017335 bytes

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