CVE-2020-0452: Google Android EXIF RCE Vulnerability

CVE-2020-0452 Overview

CVE-2020-0452 is a critical integer overflow vulnerability in the exif_entry_get_value function of exif-entry.c within Android's EXIF parsing library. This vulnerability allows for an out-of-bounds write condition that can be triggered when processing maliciously crafted image metadata. The flaw enables remote code execution without requiring any user interaction or additional execution privileges, making it particularly dangerous for applications that process remote image data.

Critical Impact

Remote code execution is possible through malicious EXIF data in images, allowing attackers to compromise Android devices running vulnerable versions without any user interaction required.

Affected Products

• Google Android 8.0
• Google Android 8.1
• Google Android 9.0
• Google Android 10.0
• Google Android 11.0
• Fedora 32
• Fedora 33

Discovery Timeline

• November 10, 2020 - CVE CVE-2020-0452 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-0452

Vulnerability Analysis

This vulnerability exists in the EXIF metadata parsing functionality of Android's media framework. The exif_entry_get_value function in exif-entry.c fails to properly validate integer values during EXIF tag processing, leading to an integer overflow condition. When the overflow occurs, it results in an undersized buffer allocation, which subsequently causes an out-of-bounds write when the actual data is copied into the buffer.

The vulnerability is classified under CWE-190 (Integer Overflow or Wraparound), which represents a common class of memory corruption vulnerabilities where arithmetic operations exceed the maximum representable value for a given data type, causing the value to wrap around.

Root Cause

The root cause lies in insufficient validation of EXIF entry size values before performing arithmetic operations. When calculating buffer sizes for EXIF data extraction, the code performs arithmetic operations on user-controlled values without checking for integer overflow conditions. This allows an attacker to craft EXIF metadata with specific values that cause the multiplication or addition operations to wrap around, resulting in a much smaller buffer allocation than required for the actual data.

Attack Vector

The attack can be executed remotely by delivering a malicious image to the target device. Any third-party application that uses Android's EXIF library to process remote image data becomes a potential attack vector. Common exploitation scenarios include:

• Malicious images shared via messaging applications
• Weaponized images hosted on websites
• Compromised image servers delivering malformed content
• Email attachments containing crafted images

The vulnerability is particularly dangerous because it requires no user interaction beyond the normal processing of image files. When a vulnerable application parses the EXIF metadata of a crafted image, the integer overflow triggers the out-of-bounds write, potentially allowing arbitrary code execution in the context of the affected application.

The attack leverages the following chain of events: a malformed EXIF entry with specially crafted size values is parsed by the exif_entry_get_value function. The integer overflow during buffer size calculation causes allocation of an undersized buffer. The subsequent data copy operation writes beyond the allocated buffer boundaries, potentially overwriting adjacent memory structures and enabling code execution.

Detection Methods for CVE-2020-0452

Indicators of Compromise

• Unusual crashes in applications processing image EXIF data, particularly in media-related services
• Unexpected memory corruption errors in system logs related to image processing
• Anomalous network activity following image file processing operations
• Detection of image files with abnormally large or suspicious EXIF entry values

Detection Strategies

• Monitor for unusual segmentation faults or memory access violations in processes handling image files
• Implement file integrity monitoring for image processing components and libraries
• Deploy network-level inspection to identify images with malformed EXIF structures
• Enable crash reporting and analyze patterns related to EXIF parsing functions

Monitoring Recommendations

• Configure application crash monitoring to alert on EXIF-related processing failures
• Implement sandbox analysis for incoming images from untrusted sources
• Monitor system logs for memory corruption indicators in media framework components
• Track security patch levels across managed Android devices to ensure CVE-2020-0452 patches are applied

How to Mitigate CVE-2020-0452

Immediate Actions Required

• Update Android devices to security patch level November 2020 or later
• Apply Fedora security updates that address CVE-2020-0452 for libexif
• Review and update any applications that bundle vulnerable versions of the libexif library
• Consider temporarily restricting image processing from untrusted sources until patches are applied

Patch Information

Google addressed this vulnerability in the Android Security Bulletin November 2020. The fix implements proper integer overflow checks before buffer allocation in the exif_entry_get_value function. Organizations should ensure all Android devices are updated to security patch level 2020-11-01 or later.

Additionally, Fedora has released updates for affected versions. See the Fedora Package Announcement for detailed update information. Gentoo users should refer to GLSA 202011-19 for applicable patches.

Workarounds

• Implement application-level EXIF parsing validation before processing images
• Deploy network security controls to scan and sanitize incoming image files
• Use application sandboxing to limit the impact of potential exploitation
• Consider disabling automatic EXIF processing in high-risk applications until patches can be applied
• Restrict image file sources to trusted origins where feasible