Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 5c43b16d8628100a…

MALICIOUS

RTF / .DOC

1.90 MB First seen: 2022-03-30
MD5: c7df91154b62532554ef640b6a13b5f4 SHA-1: 18c42148f8d83ec3d8127cc64f72ce7a78875443 SHA-256: 5c43b16d8628100afaa05108e1e0773f9be12dab54a2320cc03a8ee0fdbffe99
320 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of exploitation, including RTF_EQUATION_EDITOR and RTF_EXCESSIVE_HEX heuristics, pointing to CVE-2018-0802. The embedded OLE object data is large and heavily encoded, suggesting it hides a payload. ClamAV detection confirms this as Rtf.Exploit.CVE_2018_0802-6825822-0, indicating a known exploit targeting the Equation Editor.

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
  • \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 ~1986KB 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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000018b2.bin
1e59d0b3fd2045cd7e86cbcb212d9a7c3a95de898931313b581561ed058d8fdd		 rtf-objdata-decoded RTF \objdata at offset 0x18B2 993350 bytes

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