Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b1080c537b0184b1…

MALICIOUS

RTF / .DOC

31.6 KB First seen: 2023-02-15
MD5: f0a5006114bdbb6aed6431fe75f0579e SHA-1: a134a572919743ec75cc9ae7f0da4561e6b668f3 SHA-256: b1080c537b0184b168a46d9429f89f96de5736f4236368a7599964415e67e4a7
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically identified as related to the Equation Editor vulnerability (CVE-2017-11882). The presence of \objupdate indicates that the embedded object is designed to be activated automatically upon opening the document. The document body includes a lure instructing the user to 'Enable editing', a common tactic to bypass macro security. This combination strongly suggests the document is a dropper designed to exploit this known vulnerability to execute a malicious payload.

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_off0000548f.bin
81e8e072e12def21bf0c6e61e6c3a826a5099e3a32cd0ca0b76180c3a3df9d85		 rtf-objdata-decoded RTF \objdata at offset 0x548F 1314 bytes

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