Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fcfa8e6d6da6a05f…

MALICIOUS

RTF / .DOC

27.9 KB First seen: 2022-12-20
MD5: 9751f5d6eff300ce56fa20323c60c2c4 SHA-1: 8e3366ea870d4d8c56adc2dfddde8955f9ef5f49 SHA-256: fcfa8e6d6da6a05fd3ced82a7a77bb416231edcfdfb228f3d9641c7ca86cc5d0
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1059 Command and Scripting Interpreter T1059.005 Visual Basic T1559 Component Object Model Hijacking T1559.001 Component Object Model

The sample is an RTF document containing an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The document body contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings. The exploit likely leads to the execution of a second-stage 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_off00004e5f.bin
e5d6bed174b93af97f1e971679cdf41d55558e3e07300f16627cc08420d633e9		 rtf-objdata-decoded RTF \objdata at offset 0x4E5F 1907 bytes

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