Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 dea57daa4ee5face…

MALICIOUS

RTF / .DOC

1.88 MB First seen: 2022-04-14
MD5: 06fd085ec68f9b4cb2f169213f5f412e SHA-1: 04ca8e592a5da60bd6a6f9f1459e64f1dd44e504 SHA-256: dea57daa4ee5face0a65bc9ab098350ea3f0bf1943878a8d5a48a5ea6bf6662e
260 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: User Execution: Malicious File T1559.001 Component Object Model Hijacking: Component Object Model T1059.001 Command and Scripting Interpreter: PowerShell

The RTF document contains OLE object data and is specifically flagged as related to CVE-2017-11882, indicating exploitation of this vulnerability. The presence of a large, hex-encoded OLE object further suggests a hidden payload. The attack pattern involves luring the user to open the RTF file, which then exploits the Equation Editor vulnerability to execute a secondary payload.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1970KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000010c6.bin
ee26cdc41b767c53486d3c64e49e79657fbe4c356de397c4bc6446fb78590ecd		 rtf-objdata-decoded RTF \objdata at offset 0x10C6 985481 bytes

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