CVE-2021-32421
📋 TL;DR
CVE-2021-32421 is a heap use-after-free vulnerability in dpic's deletestringbox() function that allows attackers to execute arbitrary code or cause denial of service. This affects users of dpic 2021.01.01 who process untrusted input files. The vulnerability occurs when memory is accessed after being freed, potentially leading to memory corruption.
💻 Affected Systems
- dpic
📦 What is this software?
Dpic by Dpic Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the dpic process, potentially leading to full system compromise if dpic runs with elevated privileges.
Likely Case
Application crash (denial of service) when processing malicious input files.
If Mitigated
Limited impact if dpic runs in a sandboxed environment with minimal privileges and processes only trusted input.
🎯 Exploit Status
Exploitation requires crafting a malicious diagram file that triggers the use-after-free condition. No public exploit code has been identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in commit d317e4066c17f9ceb359b3af13264c32f6fb43cf and later versions
Vendor Advisory: https://gitlab.com/aplevich/dpic/-/issues/7
Restart Required: No
Instructions:
1. Update dpic to a version after commit d317e4066c17f9ceb359b3af13264c32f6fb43cf. 2. Recompile from source if using self-compiled version. 3. Replace existing dpic binary with patched version.
🔧 Temporary Workarounds
Input validation and sandboxing
linuxRun dpic in a sandboxed environment and only process trusted diagram files
# Example using bubblewrap on Linux: bwrap --ro-bind /usr /usr --ro-bind /lib /lib --ro-bind /lib64 /lib64 --bind $HOME $HOME --dev /dev --proc /proc --unshare-all --die-with-parent dpic input.pic
🧯 If You Can't Patch
- Restrict dpic usage to trusted users only and implement strict input validation
- Run dpic with minimal privileges (non-root user) and in isolated containers
🔍 How to Verify
Check if Vulnerable:
Check dpic version: dpic --version should show 2021.01.01. If compiled from source, check if commit d317e4066c17f9ceb359b3af13264c32f6fb43cf is included.Check Version:
dpic --versionVerify Fix Applied:
Verify dpic version is newer than 2021.01.01 or includes commit d317e4066c17f9ceb359b3af13264c32f6fb43cf. Test with known safe diagram files.📡 Detection & Monitoring
Log Indicators:
- Segmentation fault or abnormal termination of dpic process
- Memory access violation errors in system logs
Network Indicators:
- N/A - dpic is typically used locally
SIEM Query:
process.name:"dpic" AND (event.action:"segmentation_fault" OR event.action:"memory_violation")