Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 02d40c1145ed8006…

MALICIOUS

RTF / .DOC

14.2 KB First seen: 2022-08-11
MD5: a4d694221af4e1e490a035fb77a1a429 SHA-1: 980c2d5e7a58478a3ba881fcd5c747f5fdd2ffd9 SHA-256: 02d40c1145ed800637ba0e6f931fa9984b5f06dd24b57d171f671c8eec0a7112
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell T1204.002 Malicious File

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Equation Editor. The presence of OLE object data and specific RTF heuristics strongly indicate exploitation of this known vulnerability. The 'SE_ENABLE_LURE' heuristic suggests the document attempts to trick the user into enabling content, which is a common delivery mechanism for macro-based malware. The primary attack vector is the exploitation of the Equation Editor to achieve code execution.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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
  • 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_off0000207f.bin
24a8b9eeb47c15f89a79d4b2fb163fc7ac2fadbf3a8ada26dba54d0eb868ac12		 rtf-objdata-decoded RTF \objdata at offset 0x207F 1675 bytes

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