Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e5370c83aa9414d3…

MALICIOUS

RTF / .DOC

109.4 KB
MD5: de7f48fd561e707a0f9a3c39d7057551 SHA-1: 2e9e1d2eed64cf16d12072b1113644ae6ab74379 SHA-256: e5370c83aa9414d30056fc12c2f267408e828f5a953cde165841cb782f5e4559
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF file contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The heuristics indicate obfuscated Equation Editor ProgID and activation, strongly suggesting exploitation of this known vulnerability. This technique is commonly used to deliver a second-stage payload.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \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.
  • 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_off00000a6f.bin
309c79bfe3c1f569d9293fbe146776b515c7ea0b26705575686ae6e494392789		 rtf-objdata-decoded RTF \objdata at offset 0xA6F 1895 bytes

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