Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c2219a7388cab7bc…

MALICIOUS

RTF / .DOC

32.2 KB First seen: 2023-02-16
MD5: 615ad8e46a26ed62a5812a560f2a55ef SHA-1: 719a659caac2cd3a15fd817a022dcb379d9c1134 SHA-256: c2219a7388cab7bc2e297b8e4842e5be469b1698bac77def8ada0014bc9ab6d4
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The sample is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body contains a lure related to marketing strategy, and heuristic firings indicate the presence of an OLE object and an attempt to force its activation. The SE_ENABLE_LURE heuristic suggests the document instructs the user to enable editing, a common technique for malware droppers.

Heuristics 6

  • 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 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00004573.bin
2eb1ef39c427997d91b97195ae4422711dcc26bb3cef1ea397652db43c23a33b		 rtf-objdata-decoded RTF \objdata at offset 0x4573 1925 bytes

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