Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7d1854dbe78f3b7b…

MALICIOUS

RTF / .DOC

47.6 KB First seen: 2023-02-20
MD5: b8e3faafbd8cbc11fce31a201d4c8a1a SHA-1: 0fc8229cc5c9f25746de4f85f36d1332793032bc SHA-256: 7d1854dbe78f3b7b631f6dd84168b88d20b8ac12dba2ef4c7fc0693e826f2dfe
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1566.002 Phishing: Spearphishing via Service

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Equation Editor component. The presence of \objdata and \objupdate directives, along with the specific ProgID 'EQuATiOn.3', strongly indicates exploitation of this known vulnerability. This technique is commonly used to deliver secondary payloads, such as malware downloaders or droppers, by executing arbitrary code when the document is opened and the OLE object is activated.

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 1 \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_off0000530b.bin
9cf7e6732a3f93e16c9ba0f69d6f46190dfe932ef636685b8be562aa847eadea		 rtf-objdata-decoded RTF \objdata at offset 0x530B 2146 bytes

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