Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7398809e85fd3717…

MALICIOUS

RTF / .DOC

2.09 MB
MD5: dc496cbd7363e5eaded70c3b82d945b4 SHA-1: 1cba05eefbf3dd00f0e09591e676b9d2674319be SHA-256: 7398809e85fd3717f942bae422ed238f230d214359819afe88ae28e619b3b7b1
180 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This exploit is designed to execute arbitrary code, likely to download and run a secondary payload. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this exploit 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.
  • 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_off00001202.bin
1845ef988935924662433d07f966010128cc3c8c4da553430b33b824fe0dcee9		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27277 bytes
objdata_01_off0001cf27.bin
53b9f303d393dc929d79a2b5c8f4ddab6c91c8bfe1e80e0ffc1a4d210ef1046d		 rtf-objdata-decoded RTF \objdata at offset 0x1CF27 362344 bytes

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