CVE-2018-20362 in Freeware Advanced Audio Decoder
Summary
by MITRE
A NULL pointer dereference was discovered in ifilter_bank of libfaad/filtbank.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. The vulnerability causes a segmentation fault and application crash because adding to windowed output is mishandled in the EIGHT_SHORT_SEQUENCE case.
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Analysis
by VulDB Data Team • 06/20/2023
The vulnerability identified as CVE-2018-20362 represents a critical NULL pointer dereference flaw within the Freeware Advanced Audio Decoder 2 version 2.8.8 implementation. This issue resides in the ifilter_bank function located in the libfaad/filtbank.c source file, where the decoder fails to properly validate pointer references during audio frame processing. The flaw specifically manifests during the handling of EIGHT_SHORT_SEQUENCE audio data structures, which are part of the advanced audio coding standard used in various multimedia applications and streaming services.
The technical nature of this vulnerability stems from improper memory management during the windowed output processing phase of audio decoding operations. When the decoder encounters audio data structured as EIGHT_SHORT_SEQUENCE, it attempts to perform mathematical operations on windowed output values without first verifying that the necessary memory pointers have been properly initialized. This results in a segmentation fault when the application attempts to dereference a NULL pointer, causing immediate program termination and system instability. The flaw demonstrates characteristics consistent with CWE-476, which specifically addresses NULL pointer dereference vulnerabilities in software implementations.
The operational impact of this vulnerability extends beyond simple application crashes to potentially enable denial of service attacks against systems relying on FAAD2 for audio processing. Attackers could craft malicious audio files containing specifically formatted EIGHT_SHORT_SEQUENCE data structures to trigger the NULL pointer dereference, causing targeted applications to crash repeatedly. This vulnerability affects any software application that integrates FAAD2 as an audio decoding library, including media players, streaming services, and multimedia frameworks. The vulnerability's exploitation requires minimal technical expertise, making it particularly dangerous in environments where users cannot be trusted to provide sanitized audio content.
Mitigation strategies for CVE-2018-20362 should prioritize immediate software updates to FAAD2 version 2.8.9 or later, which contains the necessary patches to address the NULL pointer dereference issue. Organizations should implement comprehensive vulnerability management processes to identify all systems utilizing FAAD2 libraries and ensure timely patch deployment. Additionally, input validation mechanisms should be strengthened to sanitize audio file inputs before processing, preventing malformed data from reaching the vulnerable decoder functions. Security monitoring should include detection of unusual application crash patterns and segmentation fault occurrences that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1203 technique for "Exploitation for Privilege Escalation" when combined with other attack vectors, though the primary impact remains denial of service rather than privilege escalation.