Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 b876e30909eb2d33…

MALICIOUS

Office (OOXML) / .XLSX

878.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-06-07
MD5: b46ba5af6f815406f71fd5b86fef468c SHA-1: 4e01dc8cf99270be023868261df0274616012127 SHA-256: b876e30909eb2d33618c57523adc42c532c8e71a0b9bc3c6f773629284fd0b04
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. This object carries a payload-like stream with an anomalous header, indicating it's designed to exploit a known vulnerability. ClamAV detection confirms this as a downloader trojan. The primary attack vector is likely a spearphishing attachment leveraging the Equation Editor exploit to download and execute a secondary payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/TpLDhecNR.hj contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0
  • 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
68a3bf971cdef86b9fbbc637ab1b78c7464e6ed96ac200249996f8e72d58a6d5		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/TpLDhecNR.hj 1039872 bytes
ooxml_oleobject_00_ole10native_00.bin
7caf5b701147531307406f91dbbf601267c931c446418040240411a42b3aa6dc		 ole-package OOXML xl/embeddings/TpLDhecNR.hj Ole10Native stream: Ole10NaTive 1029546 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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