CVE-2017-9669 in apk
Summary
by MITRE
A heap overflow in apk (Alpine Linux's package manager) allows a remote attacker to cause a denial of service, or achieve code execution by crafting a malicious APKINDEX.tar.gz file.
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Analysis
by VulDB Data Team • 11/09/2019
The vulnerability identified as CVE-2017-9669 represents a critical heap overflow condition within apk, the package manager utilized by Alpine Linux distributions. This flaw exists in the parsing mechanism of APKINDEX.tar.gz files which are used to maintain package metadata and repository information. The heap overflow occurs when the apk tool processes maliciously crafted package index files, specifically during the decompression and parsing operations of these tar.gz archives. The vulnerability stems from insufficient input validation and memory management within the parsing routine, allowing attackers to manipulate memory layout through carefully constructed payload data.
The technical implementation of this vulnerability involves the manipulation of the heap memory allocation process during tar.gz file processing. When apk encounters an APKINDEX.tar.gz file, it performs decompression operations that trigger the heap overflow condition. The flaw manifests as a result of improper bounds checking during the parsing of archive metadata, particularly when handling compressed file entries that exceed expected size parameters. Attackers can exploit this by creating malicious APKINDEX.tar.gz files containing oversized or malformed entries that cause the heap allocator to write beyond allocated memory boundaries. This memory corruption can lead to arbitrary code execution or system crashes, depending on the specific memory layout and execution context.
From an operational perspective, this vulnerability presents significant risk to systems running Alpine Linux distributions that utilize the apk package manager. The remote exploitation capability means that attackers can compromise systems simply by hosting malicious package repositories or by compromising package distribution channels. The impact extends beyond simple denial of service to potentially full system compromise, as the heap overflow can be leveraged for privilege escalation or code execution within the context of the package manager process. Organizations relying on Alpine Linux for containerized environments, embedded systems, or cloud infrastructure face particular risk since these deployments often automatically update packages from remote repositories.
The vulnerability aligns with CWE-121, heap-based buffer overflow, and maps to ATT&CK technique T1059.007 for execution through command and scripting interpreter. The attack surface includes any system that processes package index files from untrusted sources, making it particularly dangerous in environments where automated package updates occur. Mitigation strategies should include immediate patching of the apk package to address the heap overflow condition, implementing strict repository validation procedures, and deploying network controls to prevent access to untrusted package repositories. Additionally, organizations should consider implementing package signature verification mechanisms and regular security audits of their package management infrastructure. The vulnerability demonstrates the critical importance of input validation in archive processing utilities and highlights the need for robust memory safety practices in system administration tools.