Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 cb55a4a7de1fc55b…

MALICIOUS

RTF / .DOC

24.9 KB First seen: 2022-12-01
MD5: 9f73c92793160df580f58a7da2fba457 SHA-1: 630c1b47cbb3c90954d6e3fef5dd851ed3d1a580 SHA-256: cb55a4a7de1fc55ba0c76877f7930bdffff0645440321a8e22b8ff5d4e96d7ac
200 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 via the Equation Editor. The document body contains a lure instructing the user to 'Enable editing' to view the content, which is a common technique to bypass macro security settings. The exploitation of CVE-2017-11882 is a critical finding.

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_off000049bd.bin
0f66d3d7dfaa73d5a5f57a1b643199af92b379fd67ba3a37f811f20ab094a7f8		 rtf-objdata-decoded RTF \objdata at offset 0x49BD 1468 bytes

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