CVE-2020-20740 – This vulnerability in PDFResurrect before versi... (How to Fix)

Q: What is the severity of CVE-2020-20740?

CVE-2020-20740 has a CVSS score of 7.8 (HIGH). This vulnerability in PDFResurrect before version 0.20 allows attackers to cause a heap buffer overflow via specially crafted PDF files due to insufficient header validation. This could lead to arbitrary code execution or denial of service. Anyone using PDFResurrect to analyze or extract data from PDF files is affected.

📋 TL;DR

This vulnerability in PDFResurrect before version 0.20 allows attackers to cause a heap buffer overflow via specially crafted PDF files due to insufficient header validation. This could lead to arbitrary code execution or denial of service. Anyone using PDFResurrect to analyze or extract data from PDF files is affected.

💻 Affected Systems

Products:

PDFResurrect

Versions: All versions before 0.20

Operating Systems: Linux, Unix-like systems, Any OS where PDFResurrect is installed

Default Config Vulnerable: ⚠️ Yes

Notes: The vulnerability exists in the core pdf_get_version() function and affects all installations of vulnerable versions.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with the privileges of the PDFResurrect process, potentially leading to full system compromise.

🟠

Likely Case

Denial of service (application crash) when processing malicious PDF files.

🟢

If Mitigated

No impact if the vulnerable version is not used or if input validation prevents malicious PDFs.

🌐 Internet-Facing: MEDIUM - PDFResurrect is typically used as a command-line tool rather than a network service, but web applications that use it to process uploaded PDFs could be exposed.

🏢 Internal Only: MEDIUM - Internal users could exploit this if they can supply malicious PDFs to vulnerable systems.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The GitHub issue includes proof-of-concept details, and heap buffer overflows are commonly exploitable for code execution.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 0.20 and later

Vendor Advisory: https://github.com/enferex/pdfresurrect/commit/1b422459f07353adce2878806d5247d9e91fb397

Restart Required: No

Instructions:

1. Download PDFResurrect 0.20 or later from GitHub. 2. Compile and install according to the project's instructions. 3. Replace any vulnerable versions with the patched version.

🔧 Temporary Workarounds

Input validation for PDF files

all

Implement strict validation of PDF file headers before processing with PDFResurrect.

Sandbox PDFResurrect execution

linux

Run PDFResurrect in a container or sandbox with limited privileges to contain potential exploitation.

docker run --read-only --cap-drop=ALL -v /path/to/pdf:/pdf:ro pdfresurrect

🧯 If You Can't Patch

Disable or remove PDFResurrect from production systems
Implement network segmentation to limit access to systems running PDFResurrect

🔍 How to Verify

Check if Vulnerable:

Check the installed PDFResurrect version: pdfresurrect --version

Check Version:

pdfresurrect --version

Verify Fix Applied:

Verify the version is 0.20 or higher and test with known malicious PDF samples.

📡 Detection & Monitoring

Log Indicators:

Application crashes of PDFResurrect
Segmentation fault errors in system logs

Network Indicators:

Unusual PDF file uploads to systems using PDFResurrect

SIEM Query:

source="system_logs" AND ("segmentation fault" OR "pdfresurrect" AND "crash")

📊 Metadata

CVE ID: CVE-2020-20740

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-787

Published: November 20, 2020

Last Updated: November 21, 2024

🔗 References

https://github.com/enferex/pdfresurrect/commit/1b422459f07353adce2878806d5247d9e91fb397 Patch,Third Party Advisory
https://github.com/enferex/pdfresurrect/issues/14 Exploit,Issue Tracking,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/12/msg00002.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JMEEEPBBGER5LPABBRVZLMCC6Z24RBXW/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZOIEVFM3SIMAEOFJKKMYH2TLZ7PXLSUD/
https://github.com/enferex/pdfresurrect/commit/1b422459f07353adce2878806d5247d9e91fb397 Patch,Third Party Advisory
https://github.com/enferex/pdfresurrect/issues/14 Exploit,Issue Tracking,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/12/msg00002.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JMEEEPBBGER5LPABBRVZLMCC6Z24RBXW/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZOIEVFM3SIMAEOFJKKMYH2TLZ7PXLSUD/

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