Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 ff99faab0691b2fc…

MALICIOUS

RTF / .DOC

538.8 KB First seen: 2022-03-22
MD5: d3033a808b591b10223ea863b3820a5c SHA-1: 817b5cedc22791f7df632cc9ba98f19b7c88e0da SHA-256: ff99faab0691b2fcbf35860fc8f7d348dcfcff04bea6d0c87f1e9b74de46a3bf
160 Risk Score

Malware Insights

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

The sample is an RTF document that contains an OLE object with automatic linking and update flags set, indicating an attempt to execute embedded content. Critical heuristic firings confirm the exploitation of CVE-2017-11882 via an Equation Editor font record overflow. This vulnerability allows for arbitrary code execution, which is the primary mechanism for delivering a malicious payload. No scripts were extracted, and the document body was truncated, but the exploit itself is sufficient evidence of malicious intent.

Heuristics 4

  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001a6d.bin
4b0fdd70ecbd531c3fec7b795e9a063c9212f463ebf17712c19b7356900b87f5
rtf-objdata-decoded RTF \objdata at offset 0x1A6D 4152 bytes