Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3f4b4fa4aa24877e…

MALICIOUS

Office (OOXML)

350.5 KB Created: 2020-08-17 09:05:28 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-15
MD5: 017f04558ed9fbf55a9de7464efb1478 SHA-1: 461ed30ecfd0e2ed795e11bbddc4ea27487255df SHA-256: 3f4b4fa4aa24877ecbd098ad58376d2ee8fd4cfe764d5cfc331b3cfbf68afe05
202 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an Excel document containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798, a vulnerability in the Equation Editor. This exploit likely leads to the execution of a secondary payload, as suggested by the high entropy and shellcode candidate findings in the extracted OLE streams. The ClamAV detection further confirms its malicious nature as a dropper.

Heuristics 6

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
  • ClamAV: Xls.Dropper.Generic-9823786-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Generic-9823786-0
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is an exploit-shaped Equation/OLE payload container seen in malicious OOXML samples. It is not assigned to a specific CVE unless the MTEF/Equation Native primitive also matches.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • Suspicious extracted artifact info 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 262656 bytes
SHA-256: e27b7e17c3d19079255bb60f44351c9a7f313c8b83be779ed2b379f340e74a40
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
ooxml_oleobject_00_ole10native_00.bin ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OlE10NaTive 258490 bytes
SHA-256: c5dc8ed4b683c0556e7cfd203c6418c71f6cd06459bfb04a98f42bdd957cbd9f
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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