Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e3133c9d59c5b8cd…

MALICIOUS

RTF / .DOC

1.91 MB First seen: 2022-03-16
MD5: 2b3e159b1742a1b0f1118ddf7e9b1ef3 SHA-1: d88e656cb61952537df917ca9393f09a98edde33 SHA-256: e3133c9d59c5b8cde68bf5bfe4356ec37ed7b4f559f1260fc10e94d6fc566c78
240 Risk Score

Malware Insights

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

The RTF file contains OLE object data and is specifically flagged for exploiting CVE-2017-11882 using the Equation Editor. The presence of a large, hex-encoded OLE object further suggests a hidden payload. The attack pattern involves leveraging this known vulnerability to execute arbitrary code, likely leading to the download and execution of a second-stage 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.
  • \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 ~1994KB 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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001879.bin
17127f8fae30dae9edab12783840615c7678afe50e451eb71b9a9c1308a98c2e		 rtf-objdata-decoded RTF \objdata at offset 0x1879 997301 bytes

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