CVE-2017-15565

What it actually does

NULL pointer dereference in GfxImageColorMap::getGrayLine() during processing of crafted PDF documents leads to memory corruption that can result in denial of service or arbitrary code execution.

Why it matters to the business

Attackers can compromise systems that render untrusted PDFs, potentially leading to full system takeover, data theft, or ransomware deployment on outdated browsers and PDF viewers.

How an attack unfolds

An attacker crafts a malicious PDF that triggers the vulnerable code path in Poppler's GfxState.cc; when a victim opens the document in an affected application such as Firefox, the null dereference occurs and can be leveraged for code execution. Public exploits exist and the issue has been known since 2017.

How to fix it

Upgrade Firefox on Ubuntu 14.04 LTS to version 57.0+build4-0ubuntu0.14.04.4 or later. For any other Poppler-based applications, update to a build containing the fix for CVE-2017-15565. Disable PDF rendering plugins where feasible until patches are applied.

How to confirm the fix worked

Verify installed Firefox version matches or exceeds the fixed package; reprocess known-good and known-bad test PDFs in a sandboxed environment and confirm absence of crashes or unexpected memory access in GfxState.cc.

Typical attack path

1. Create a crafted PDF that reaches GfxImageColorMap::getGrayLine with invalid color map data
2. Host or deliver the PDF via email attachment, web download, or drive-by link
3. Victim opens the PDF in an affected Firefox or Poppler-based viewer
4. Trigger the null dereference and use memory corruption primitives for code execution
5. Establish persistence or exfiltrate data

How to detect it

Inspect browser and PDF viewer crash logs for faults originating in GfxState.cc or GfxImageColorMap; correlate with inbound PDF files from untrusted sources and look for post-crash process behavior indicative of exploitation.

• GfxImageColorMap::getGrayLine
• GfxState.cc
• poppler null dereference crash signature

What your security team should do

• Immediately deploy the listed Firefox update across all Ubuntu 14.04 systems
• Block or sandbox PDF handling from untrusted sources until patching is complete
• Monitor for exploitation attempts using available public proof-of-concept code
• Review and retire legacy PDF rendering libraries that depend on the vulnerable Poppler version