Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c4fb72854cb3f3ad…

MALICIOUS

RTF / .DOC

46.0 KB
MD5: f81dc3b82e36c1a5acc3f9f02b44c39c SHA-1: c392bbcd34b35534e341edd0cf04eec9fc5c43ad SHA-256: c4fb72854cb3f3adc48c5a8c0d9f5619ec0f050c6ba618639df28d3372de2aa9
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). The presence of ".objdata" and ".objupdate" directives, along with the critical RTF_EQUATION_EDITOR heuristic, strongly indicates exploitation of this known Microsoft Office vulnerability. This technique is commonly used to deliver a second-stage payload.

Heuristics 5

  • 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.
  • 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.
  • 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_off000017da.bin
315851718ab3a6fc1df1b086e4da07ded38bd3476f0d38cbeacf7c886f043c47
rtf-objdata-decoded RTF \objdata at offset 0x17DA 1413 bytes