Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 733c3892688347a3…

MALICIOUS

RTF / .DOC

14.0 KB First seen: 2021-09-25
MD5: b1568e9e4fb2da868a024791ae7a83f3 SHA-1: 550253943375e6ece1bf7130a9cdf0ab49a64183 SHA-256: 733c3892688347a33e76eb41cad96d9cb4ad587ac941a600e37834fcf1af0b08
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. This exploit is designed to execute a malicious payload, likely a second-stage malware, directly on the victim's machine. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this attack vector.

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.
  • Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR
    RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
  • \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_off00000765.bin
5aad65e1930dc16edfbcef4ca38eba86cb09fc6852dc84c49b96c3c97b141e3a		 rtf-objdata-decoded RTF \objdata at offset 0x765 2037 bytes

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