CVE-2016-8703 in potrace
Summary
by MITRE
Heap-based buffer overflow in the bm_readbody_bmp function in bitmap_io.c in potrace before 1.13 allows remote attackers to have unspecified impact via a crafted BMP image, a different vulnerability than CVE-2016-8698, CVE-2016-8699, CVE-2016-8700, CVE-2016-8701, and CVE-2016-8702.
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Analysis
by VulDB Data Team • 08/08/2020
The heap-based buffer overflow vulnerability identified as CVE-2016-8703 affects the potrace library version 1.12 and earlier, specifically within the bm_readbody_bmp function located in bitmap_io.c. This vulnerability represents a critical security flaw that enables remote attackers to execute arbitrary code or cause system instability through the manipulation of BMP image files. The flaw occurs during the processing of bitmap image data when the application fails to properly validate the size parameters of the incoming image data, leading to memory corruption that can be exploited to overwrite adjacent heap memory regions.
The technical implementation of this vulnerability stems from inadequate bounds checking within the bitmap reading functionality. When potrace processes a malformed BMP image, the bm_readbody_bmp function attempts to allocate heap memory based on potentially malicious size values extracted from the image header. This creates a scenario where an attacker can craft a specially formatted BMP file that contains oversized dimensions or incorrect metadata, causing the application to allocate insufficient memory for the image data. The subsequent write operations into this improperly sized buffer result in heap corruption that can be leveraged for code execution or denial of service attacks.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can be exploited in various contexts where potrace is used for image processing. The vulnerability affects systems that process user-uploaded BMP images or handle image conversion tasks, making it particularly dangerous in web applications, document processing systems, and image manipulation software. Attackers can exploit this flaw without requiring local access, making it a significant concern for applications that handle untrusted image data from external sources. The unspecified impact mentioned in the CVE description reflects the potential for various outcomes including system crashes, privilege escalation, or arbitrary code execution depending on the specific memory layout and exploitation techniques employed.
Mitigation strategies for CVE-2016-8703 should focus on immediate software updates to version 1.13 or later, which contains the necessary patches to address the heap overflow vulnerability. Organizations should also implement input validation measures that verify image file headers and dimensions before processing, along with memory protection mechanisms such as stack canaries and address space layout randomization. The vulnerability aligns with CWE-121, heap-based buffer overflow, and can be mapped to ATT&CK technique T1203, Exploitation for Client Execution, when exploited in web-based attack scenarios. Additional defensive measures include sandboxing image processing operations, implementing strict file format validation, and monitoring for unusual memory allocation patterns that may indicate exploitation attempts. System administrators should also consider network-level filtering to prevent the processing of untrusted image files when possible, and maintain comprehensive logging of image processing activities for security monitoring purposes.