Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 197675a38d150886…

MALICIOUS

RTF / .DOC

1.58 MB First seen: 2022-04-07
MD5: f6a77c1c41921b3a54e256ac03812c05 SHA-1: 37d804e8714d98e72e5a9a7510ab302d80e664ec SHA-256: 197675a38d15088683021654f9b1ce1e7caf19089a251d1668003cbd792ee0f6
340 Risk Score

Malware Insights

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

The sample is an RTF document containing embedded OLE objects, specifically triggering heuristics related to Equation Editor vulnerabilities (CVE_2018_0802). The presence of large, hex-encoded data within OLE objects and the ClamAV detection signature strongly indicate exploitation for client execution. The embedded OLE object likely serves as a dropper for a second-stage payload, though the exact download mechanism is not detailed in the provided evidence.

Heuristics 8

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • Equation Editor CLSID critical RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • ClamAV: Rtf.Exploit.CVE_2018_0802-6825822-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2018_0802-6825822-0
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1648KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000fc3.bin
64da1dbf002e296fd5058b332d7ef96d2d75ea8b764d43d1defc9e2265901351		 rtf-objdata-decoded RTF \objdata at offset 0xFC3 824377 bytes

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