Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 5e4b70565f5e7b99…

MALICIOUS

RTF / .DOC

2.21 MB
MD5: 1a0dbf4562b2d0c384b3cd56b5093d27 SHA-1: ca7aa3291a56afaf2d3f59eb94f6755137038a28 SHA-256: 5e4b70565f5e7b99197697b64276dad411da66f31bcbdc2d4fb088efe21d9b41
180 Risk Score

Malware Insights

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

The file is an RTF document that contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability related to Equation Editor. This exploit is designed to execute arbitrary code, likely leading to the download and execution of a secondary payload. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates exploitation of this known vulnerability.

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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001116.bin
ae5cb80487f9d6e929b1e67fd712c08887a57f74f731b68c549c84e2bdc4ae34		 rtf-objdata-decoded RTF \objdata at offset 0x1116 26900 bytes
objdata_01_off0001c6fd.bin
fe43efbadd674765243cb2580d9955cd54bcbea3b2eb0d6d648fe532cb7ef883		 rtf-objdata-decoded RTF \objdata at offset 0x1C6FD 476202 bytes

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