CVE-2024-21633 is a high-severity path traversal vulnerability (CWE-22) found in Apktool, a widely used open-source tool for reverse engineering Android APK files. The vulnerability affects Apktool versions 2.9.1 and earlier. Apktool determines the output path for resource files based on their resource names. An attacker can manipulate these resource names to craft file paths that traverse directories outside the intended output directory. This allows the attacker to write or overwrite arbitrary files on the filesystem where Apktool is executed, provided the user running Apktool has write permissions to those locations. The vulnerability requires local access to run Apktool with a crafted APK or resource files. Exploitation also requires that the current working directory or the username is known or predictable, which is common in many user environments. The vulnerability impacts confidentiality, integrity, and availability since arbitrary files can be overwritten, potentially leading to code execution, privilege escalation, or denial of service. A patch has been committed (commit d348c43b24a9de350ff6e5bd610545a10c1fc712) to fix the improper path validation. No known exploits are reported in the wild yet. The CVSS v3.1 score is 7.8, reflecting the high impact and relatively low attack complexity, although local access and user interaction are required.

For European organizations, this vulnerability poses a significant risk especially for security researchers, developers, or malware analysts who use Apktool for legitimate reverse engineering tasks. If an attacker can trick a user into processing a maliciously crafted APK or resource file, they could overwrite critical files on the user's system, potentially leading to arbitrary code execution or system compromise. This could result in data breaches, disruption of development or security workflows, and potential lateral movement within networks if compromised hosts have elevated privileges. Organizations relying on Apktool in their security operations or development pipelines must be aware of this risk. Since Apktool is a developer and analyst tool, the impact is more pronounced in environments where Apktool is used on shared or sensitive systems. The vulnerability does not directly affect production Android devices but targets the host systems running Apktool. European organizations with active Android development or security research teams are particularly at risk.

1. Immediately upgrade Apktool to a version later than 2.9.1 that includes the patch for CVE-2024-21633. If an official patched release is not yet available, apply the patch from commit d348c43b24a9de350ff6e5bd610545a10c1fc712 manually. 2. Restrict Apktool usage to trusted users and environments only, minimizing exposure to untrusted APK files or resource inputs. 3. Run Apktool in isolated environments such as containers or virtual machines with limited filesystem permissions to contain potential exploitation. 4. Implement strict filesystem permissions on user directories to prevent unauthorized file overwrites. 5. Educate developers and analysts about the risks of processing untrusted APKs and encourage scanning inputs with antivirus or sandboxing tools before use. 6. Monitor file system integrity on systems running Apktool to detect unexpected file modifications. 7. Incorporate Apktool usage into broader endpoint security monitoring to detect suspicious activities related to file writes or privilege escalations.