zsteg 摘取数据
$ zsteg -h
Usage: zsteg [options] filename.png [param_string]
-c, --channels X channels (R/G/B/A) or any combination, comma separated
valid values: r,g,b,a,rg,rgb,bgr,rgba,...
-l, --limit N limit bytes checked, 0 = no limit (default: 256)
-b, --bits N number of bits (1..8), single value or '1,3,5' or '1-8'
--lsb least significant BIT comes first
--msb most significant BIT comes first
-P, --prime analyze/extract only prime bytes/pixels
-a, --all try all known methods
-o, --order X pixel iteration order (default: 'auto')
valid values: ALL,xy,yx,XY,YX,xY,Xy,bY,...
-E, --extract NAME extract specified payload, NAME is like '1b,rgb,lsb'
-v, --verbose Run verbosely (can be used multiple times)
-q, --quiet Silent any warnings (can be used multiple times)
-C, --[no-]color Force (or disable) color output (default: auto)
PARAMS SHORTCUT
zsteg fname.png 2b,b,lsb,xy ==> --bits 2 --channel b --lsb --order xy
在 Kali Linux 中，自带 Ruby 的包管理器 RubyGems，因此直接用以下命令安装后即可使用：
$ gem install zsteg
下载附件得到一张bmp格式的图片