Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fc8b0c765bad7903…

MALICIOUS

RTF / .DOC

20.9 KB
MD5: 24872831ee195b2e47de970c480da95a SHA-1: 630e777e9aa508c80c276a38f03e7ffc3f76f574 SHA-256: fc8b0c765bad790308ddd1865cc47009348aef515b4edbd2bee5c17dbecca1a7
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known Microsoft Office vulnerability. The objupdate directive forces the OLE object to activate, leading to arbitrary code execution.

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_off000015d4.bin
982123dab46de072af9ddf652931ff0c0599e80b3ee31f1fd9f8e5793934f0fd
rtf-objdata-decoded RTF \objdata at offset 0x15D4 2421 bytes