Scans a flat, 32-bit binary file and attempts to calculate the base address of the image. Looks for ASCII English strings then finds the greatest intersection of all 32-bit words interpreted as pointers and the offsets of the strings.
This works rather well on some ARM (non-thumb) binaries. It's a very simple heuristic that attempts to use as little information about the file as possible from the target binary. As such, it isn't going to work miracles.
Scan a flat 32-bit binary and attempt to brute-force the base address via string/pointer comparison. Based on the excellent basefind.py by mncoppola. USAGE: rbasefind [FLAGS] [OPTIONS] <INPUT> FLAGS: -b, --bigendian Interpret as big-endian (default is little) -h, --help Prints help information -p, --progress Show progress -V, --version Prints version information OPTIONS: -n, --maxmatches <LEN> Maximum matches to display (default is 10) -m, --minstrlen <LEN> Minimum string search length (default is 10) -o, --offset <LEN> Scan every N (power of 2) addresses. (default is 0x1000) -t, --threads <NUM_THREADS> # of threads to spawn. (default is # of cpu cores) ARGS: <INPUT> The input binary to scan
time ./rbasefind fw.bin Located 2355 strings Located 372822 pointers Scanning with 8 threads... 0x00002000: 2195 0x00001000: 103 0x00000000: 102 0x00003000: 101 0x00004000: 90 0x45e95000: 74 0x45e93000: 73 0x00006000: 64 0x00005000: 59 0x45ec3000: 58 real 0m40.937s user 5m20.908s sys 0m0.035s
0x00002000 was the correct base address for this binary.
For large binaries, the default scan may take too long. The search size can be dialed down, at the expense of "accuracy", via specifying a minimum string length. i.e.,
time ./target/release/rbasefind fw_all.bin -m 100 Located 7 strings Located 372822 pointers Scanning with 8 threads... 0x00002000: 4 0x2ae7b000: 2 0xffe54000: 1 0xfba46000: 1 0xfb9c3000: 1 0xfb80a000: 1 0xfafe6000: 1 0xfafe0000: 1 0xfae3b000: 1 0xfae13000: 1 real 0m0.149s user 0m0.751s sys 0m0.012s
- Some form of auto mode. Detect endianness based on highest intersection. Auto decrease offset in window around highest match.