Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 23f74981d40afa04…

MALICIOUS

RTF / .DOC

1.97 MB
MD5: 3ae089494d820c514ba135503b99d51d SHA-1: 681700e012a038c356dbf8f052c64abb206e9aa5 SHA-256: 23f74981d40afa04ca66f227ddaf65e1bdd7e90fcec4a25a1e9c58ef240fd03c
220 Risk Score

Malware Insights

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

The RTF document contains multiple heuristics indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor OLE object. The presence of ".objupdate" and a large amount of hex-encoded data within ".objdata" sections further suggests the embedding of a malicious payload. The decoded OLE object's native payload is associated with Equation Editor, strongly pointing to this specific vulnerability.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \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 ~2062KB 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_off000000dc.bin
dac9a4ea00eff66b67ea332e0aed4a2052131f6d6525273810e20cd915f04e2b		 rtf-objdata-decoded RTF \objdata at offset 0xDC 1031101 bytes

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