Malicious RTF — malware analysis report

Static analysis result for SHA-256 12bced4206ef92d6…

MALICIOUS

RTF

1.04 MB First seen: 2022-08-29
MD5: c6fe6f8c3f84320e888a3510e88d344e SHA-1: 419001d9c2af18278d35e7abf4a015856106bfab SHA-256: 12bced4206ef92d6fc82e0e92e4b4793e43a90e0d9badb82f671df381c814805
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File Execution T1566.001 Phishing: Spearphishing Attachment

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability related to Equation Editor. This exploit is designed to execute arbitrary code, likely to download and run a secondary payload. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates exploitation of this known vulnerability.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000129e.bin
8711eba1cd765389d1dd2880a10c99df87f5fb077d9b4e725361f1a27b9f1fbf		 rtf-objdata-decoded RTF \objdata at offset 0x129E 73236 bytes
objdata_01_off0002b044.bin
e1fc1a4c0e67e69e3fb71023b7446271b7980a05bfadf3f1c66142aaf4530e1c		 rtf-objdata-decoded RTF \objdata at offset 0x2B044 187172 bytes

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