Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 eb265ebe4e52ad37…

MALICIOUS

RTF / .DOC

1.95 MB First seen: 2022-02-23
MD5: 3123c3aff4e0cae7ad060a3691c06079 SHA-1: f8b170216a206896c54e1dfc462322ec9366ea6f SHA-256: eb265ebe4e52ad374ed1067c696a0893017e17e6584761b645a308aaa9462df8
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

This RTF document contains an embedded OLE object that exploits CVE-2017-11882. The embedded object, identified as Equation.3, is designed to execute a malicious script. The script appears to be a VBScript that attempts to reconstruct and execute code, potentially downloading a second-stage payload. The reconstructed string 'eval("replace(WScript.ScriptFullname,WScript.ScriptName,"")")' suggests dynamic code execution. The presence of 'C:\Path\Client.vbs' indicates a potential dropped file or script name.

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_off00001347.bin
afe12c2fce03dcaa79cc03fc90ae219b2af850f1bb83d7ce198e6dd298c133ea		 rtf-objdata-decoded RTF \objdata at offset 0x1347 27153 bytes
objdata_01_off0001a174.bin
e5b20554568dfaf96065e21a1c2de6ba78d90f5cb8e6ca15fd00dcd61633cdac		 rtf-objdata-decoded RTF \objdata at offset 0x1A174 461165 bytes

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