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Add rule for zlib fast inflate #1142

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Add rule for zlib fast inflate #1142

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113d6e6
Add rule for zlib fast inflate
priyank766 Mar 15, 2026
24857cc
Refine zlib fast inflate rule
priyank766 Mar 15, 2026
ea00ed6
Remove issue reference from zlib fast inflate rule
priyank766 Mar 19, 2026
913b041
fix(rule): remove unmatched features from zlib fast inflate
priyank766 Mar 27, 2026
0be98c0
fix(rule): replace bytes with mnemonic for zlib fast inflate
priyank766 Mar 31, 2026
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25 changes: 25 additions & 0 deletions data-manipulation/compression/decompress-data-using-zlib-fast-inflate.yml
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Original file line number Diff line number Diff line change
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rule:
meta:
name: decompress data using ZLIB fast inflate
namespace: data-manipulation/compression
authors:
- priyank766
description: detects Chris Anderson's x86 assembly implementation of zlib inflate_fast
scopes:
static: function
dynamic: unsupported # requires bytes features
mbc:
- Data::Decompress Data [C0025]
references:
- https://github.com/madler/zlib/blob/cacf7f1d4e3d44d871b605da3b647f07d718623f/contrib/masmx86/inffas32.asm
- https://github.com/mandiant/capa-rules/issues/494
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examples:
- c2ba065654f13612ae63bca7f972ea91c6fe97291caeaaa3a28a180fb1912b3a.dll_:0x3FE40
features:
- and:
- string: "Fast decoding Code from Chris Anderson"
- string: "invalid literal/length code"
- string: "invalid distance code"
- string: "invalid distance too far back"
- bytes: 0F A2 81 FB 47 65 6E 75 75 38 81 F9 6E 74 65 6C 75 30 81 FA 69 6E 65 49 75 28 = cpuid GenuineIntel checks before enabling MMX
- bytes: 00 00 00 00 01 00 00 00 03 00 00 00 07 00 00 00 0F 00 00 00 1F 00 00 00 3F 00 00 00 = inflate_fast_mask table prefix
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