Win.Trojan.Zusy-704 — Office (OOXML) malware analysis

Static analysis result for SHA-256 3fbb61c2ae12c5f9…

MALICIOUS

Office (OOXML)

634.5 KB Created: 2015-08-11 06:32:00 UTC Authoring application: Microsoft Office Outlook 12.0000 First seen: 2015-09-15
MD5: 130c46ca2a325dc0c84e0ad2d3c8eb40 SHA-1: 59dac029e6fa63327acc18fbb866a95a2a1e618e SHA-256: 3fbb61c2ae12c5f978cc021ff1b7e3ea4591508a23ebbd12a56898aaf3c59b52
284 Risk Score

Malware Insights

Win.Trojan.Zusy-704 · confidence 95%

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample contains an embedded OLE object that functions as a script dropper, indicated by the 'OFFICE_PACKAGE_SCRIPT_DROPPER' and 'OFFICE_PACKAGE_RISKY_FILE' heuristics. This object is configured to download and execute a payload named 'AdobeReader.exe', likely from one of the embedded URLs. ClamAV detection confirms this as Win.Trojan.Zusy-704, suggesting a trojan downloader or dropper.

Heuristics 7

  • ClamAV: Win.Trojan.Zusy-704 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Zusy-704
  • Ole10Native package payload is a download-and-execute script critical OFFICE_PACKAGE_SCRIPT_DROPPER
    The OLE Package's embedded payload contains a script that hosts a shell (PowerShell/WScript/mshta), fetches a remote resource, and executes it — a download-and-run dropper. Embedding such a script inside an Office document via the Object Packager is a direct user-execution delivery technique (MITRE T1204.002), not a benign attachment.
  • Ole10Native package drops an auto-executable payload critical OFFICE_PACKAGE_RISKY_FILE
    OLE Package displayName or fullPath ends in a directly auto-executable extension (a runnable binary or a script the default shell host runs on double-click). Embedding such a payload inside an Office document has no benign authoring use — it is a malware-delivery dropper.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • 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.
  • Payload URL recovered from embedded OLE object (5 URLs) info OOXML_EMBEDDED_OBJECT_URL
    An embedded OLE object (xl/word/ppt embeddings) carries a next-stage download URL in its Ole10Native/Package stream — stored literally (incl. UTF-16) or base64-encoded — which the package-level URL sweep does not see. Surfaced as an IOC; self-validating (only real payload hosts).
  • 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://ocsp.thawte.com0 Embedded OLE package script
    • http://ts-ocsp.ws.symantec.com07Embedded OLE package script
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://crl.thawte.com/ThawteTimestampingCA.crl0Embedded OLE package script
    • http://ts-aia.ws.symantec.com/tss-ca-g2.cer0Embedded OLE package script
    • http://ts-crl.ws.symantec.com/tss-ca-g2.crl0Embedded OLE package script
    • http://ts-crl.ws.symantec.com/tss-ca-g2.crl0(In document text (OOXML body / shared strings)

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin ooxml-ole-object OOXML embedded OLE part: word/embeddings/oleObject1.bin 911872 bytes
SHA-256: 60645209a87629f892fb08c31eeba4dfb0138cb357d264994d8145edecf3a18e
Detection
ClamAV: Win.Trojan.Zusy-704
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_STR_GETPROCADDRESS, SC_STR_SHELLEXEC, SC_GETPC_CALL Static shellcode analysis recovered API/import strings: kernel32.dll, advapi32.dll, shell32.dll, KERNEL32.DLL, ADVAPI32.DLL, GetProcAddress Carved artifact entropy is 7.98, consistent with packed or encrypted content.
ooxml_oleobject_00_ole10native_00.bin ole-package OOXML word/embeddings/oleObject1.bin Ole10Native stream: Ole10Native 895509 bytes
SHA-256: b60e278fd894457d44043f19f5ec8ceef059ffde0b2b28cfe733c2b9cb0353e7
Detection
ClamAV: Win.Trojan.Zusy-704
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_STR_GETPROCADDRESS, SC_STR_SHELLEXEC, SC_GETPC_CALL Static shellcode analysis recovered API/import strings: kernel32.dll, advapi32.dll, shell32.dll, KERNEL32.DLL, ADVAPI32.DLL, GetProcAddress Carved artifact entropy is 8.00, consistent with packed or encrypted content.
emf_00.emf ooxml-emf OOXML EMF part: word/media/image1.emf 5384 bytes
SHA-256: 43c8a08c263e2b3ab3d248cbdee7bbf43c19d2758bc8743ce6a17b1bd119b514

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