FuzzCoder: Byte-level Fuzzing Test via Large Language Model
Authors: name: Liqun Yang, name: Jian Yang, name: Chaoren Wei, name: Guanglin Niu, name: Ge Zhang, name: Yunli Wang, name: Linzheng ChaI, name: Wanxu Xia, name: Hongcheng Guo, name: Shun Zhang, name: Jiaheng Liu, name: Yuwei Yin, name: Junran Peng, name: Jiaxin Ma, name: Liang Sun, name: Zhoujun Li

Fuzzing is an important dynamic program analysis technique designed for
finding vulnerabilities in complex software. Fuzzing involves presenting a
target program with crafted malicious input to cause crashes, buffer overflows,
memory errors, and exceptions. Crafting malicious inputs in an efficient manner
is a difficult open problem and the best approaches often apply uniform random
mutations to pre-existing valid inputs. In this work, we propose to adopt
fine-tuned large language models (FuzzCoder) to learn patterns in the input
files from successful attacks to guide future fuzzing explorations.
Specifically, we develop a framework to leverage the code LLMs to guide the
mutation process of inputs in fuzzing. The mutation process is formulated as
the sequence-to-sequence modeling, where LLM receives a sequence of bytes and
then outputs the mutated byte sequence. FuzzCoder is fine-tuned on the created
instruction dataset (Fuzz-Instruct), where the successful fuzzing history is
collected from the heuristic fuzzing tool. FuzzCoder can predict mutation
locations and strategies locations in input files to trigger abnormal behaviors
of the program. Experimental results show that FuzzCoder based on AFL (American
Fuzzy Lop) gain significant improvements in terms of effective proportion of
mutation (EPM) and number of crashes (NC) for various input formats including
ELF, JPG, MP3, and XML.