Office (OLE) / .XLS malware analysis — malicious · 605f96d3bbda4a2c

MALICIOUS

Office (OLE) / .XLS

313.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel

MD5: 7f75f3c16ab40c0b0fc4b29abc5c3433 SHA-1: a49ff597ed03ad9ec1fcf967531a914bbd00b5e7 SHA-256: 605f96d3bbda4a2c1d3404feba113951193ff43e0ecf1d916433eb69dc3599c7

282 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro-enabled workbook that automatically executes upon opening via the Auto_Open entry. It leverages the URLDownloadToFileA API to download a file from 'https://tiesta.in/ds/291120.gif' to 'C:\ProgramData\Freyrgb.dll'. Subsequently, it executes the downloaded file using 'regsvr32 -s C:\ProgramData\Freyrgb.dll', indicating a downloader functionality.

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.
ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
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.
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 https://tiesta.in/ds/291120.gif

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `6b210754878c93b9fd2b7ca4692041f142e3090caa22e3cd8ad7cdde6e2f4e8e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	981 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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