Tag: AFL++

AFL_SKIP_BIN_CHECK

  • Haco
  • December 22, 2025
  • 4 min read

export AFL_SKIP_BIN_CHECK=1 is an environment variable setting that tells AFL++ to stop complaining that your target program doesn't look like it was compiled with AFL. By default, AFL++ checks your target binary for specific "instrumentation" markers before it starts. If it doesn't find them, it assumes you made a mistake (like compiling with gcc instead of afl-cc) and refuses to run to save you from wasting time. When should you use this? You generally should not use this unless you know exactly why. However, here are the valid…

AFL Coverage Instrumentation Callback

  • Haco
  • December 22, 2025
  • 14 min read

0000000000000bc0 <bbCallback>: bc0: 90000102 adrp x2, 20000 <_exit@GLIBC_2.17> bc4: f9404c43 ldr x3, [x2, #152] bc8: b4000263 cbz x3, c14 <bbCallback+0x54> bcc: d53bd042 mrs x2, tpidr_el0 bd0: a9bf7bfd stp x29, x30, [sp, #-16]! bd4: 12003c01 and w1, w0, #0xffff bd8: 910003fd mov x29, sp bdc: 90000100 adrp x0, 20000 <_exit@GLIBC_2.17> be0: f9403404 ldr x4, [x0, #104] be4: 9101a000 add x0, x0, #0x68 be8: d63f0080 blr x4 bec: 78606844 ldrh w4, [x2, x0] bf0: 53017c25 lsr w5, w1, #1 bf4: 78206845 strh w5, [x2, x0] bf8: 4a040021 eor w1, w1,…