CVE-2014-0145 in QEMU
Summary
by MITRE
Multiple buffer overflows in QEMU before 1.7.2 and 2.x before 2.0.0, allow local users to cause a denial of service (crash) or possibly execute arbitrary code via a large (1) L1 table in the qcow2_snapshot_load_tmp in the QCOW 2 block driver (block/qcow2-snapshot.c) or (2) uncompressed chunk, (3) chunk length, or (4) number of sectors in the DMG block driver (block/dmg.c).
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Analysis
by VulDB Data Team • 06/16/2021
CVE-2014-0145 represents a critical vulnerability affecting QEMU virtualization software versions prior to 1.7.2 and 2.x versions before 2.0.0, where multiple buffer overflows exist within the QCOW2 and DMG block drivers. This vulnerability stems from insufficient input validation and boundary checking in the handling of disk image metadata, specifically when processing snapshot operations and chunk descriptors. The flaw manifests when QEMU processes malformed qcow2 snapshot files or DMG disk images containing oversized L1 tables, uncompressed chunks, chunk length specifications, or sector counts that exceed allocated buffer boundaries. These buffer overflows occur in the qcow2_snapshot_load_tmp function within block/qcow2-snapshot.c and in the DMG block driver implementation at block/dmg.c, creating opportunities for both denial of service conditions and potential arbitrary code execution.
The technical implementation of this vulnerability involves the exploitation of unchecked integer values during the parsing of disk image metadata structures. In the QCOW2 driver, when processing L1 table entries, the code fails to validate that the table size parameter does not exceed the allocated memory buffer, allowing attackers to craft malicious qcow2 files that trigger memory corruption during snapshot loading operations. Similarly, the DMG driver contains comparable vulnerabilities where uncompressed chunk sizes, chunk length values, and sector counts are processed without adequate boundary checks, leading to stack or heap buffer overflows. These conditions create memory corruption that can be leveraged by attackers to redirect execution flow or cause system crashes.
The operational impact of CVE-2014-0145 extends beyond simple denial of service scenarios, as the buffer overflows present potential paths for privilege escalation and arbitrary code execution within the virtualized environment. An attacker with access to create or modify qcow2 or DMG disk images could potentially craft malicious images that, when loaded by a vulnerable QEMU instance, would trigger the buffer overflows and allow for code execution with the privileges of the QEMU process. This poses significant risks in cloud computing environments where multiple virtual machines share the same host system, as successful exploitation could enable attackers to compromise the host system or other virtual machines running on the same infrastructure. The vulnerability affects both local users who can manipulate disk images and remote attackers who can influence the creation of disk images in shared environments.
Mitigation strategies for CVE-2014-0145 require immediate patching of QEMU installations to versions 1.7.2 or 2.0.0 and later, which contain the necessary fixes for the buffer overflow conditions. Organizations should implement strict disk image validation procedures and avoid loading untrusted or unverified qcow2 and DMG images in production environments. Network segmentation and access controls should be enforced to limit who can create or modify virtual disk images within virtualization infrastructure. Additionally, monitoring systems should be deployed to detect unusual disk image creation patterns or unexpected QEMU crash events that might indicate exploitation attempts. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow and CWE-122 Heap-based Buffer Overflow categories, and represents a technique commonly categorized under ATT&CK tactic TA0005 (Defense Evasion) and technique T1059 (Command and Scripting Interpreter) when exploited for code execution purposes.