Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d0a1c1a60a1fc6a0…

MALICIOUS

RTF / .DOC

28.3 KB First seen: 2023-02-23
MD5: 1d80c56b129beeea2dc026bcdc12fbf0 SHA-1: 4a14723d19b30cb91dfbecd3d497c44ed0099711 SHA-256: d0a1c1a60a1fc6a0760ecf3db863a5586002fdff169bd2baff06fd91c7d14ba1
200 Risk Score

Malware Insights

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

The sample is an RTF document that exploits the CVE-2017-11882 vulnerability through an embedded Equation Editor OLE object. The document body contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security. The embedded object's class name 'equaTiOn.3' is a strong indicator of this specific exploit.

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_off000020bd.bin
c94c994eb7e32bd8a12b7d27332b4a41c483544004af4f19c4ea247bd30d9181		 rtf-objdata-decoded RTF \objdata at offset 0x20BD 1519 bytes

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