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Add dynsym_entries and dynsym ELF module attributes #196

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Jan 31, 2022
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Add dynsym_entries and dynsym ELF module attributes #196

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55 changes: 55 additions & 0 deletions modules/module_elf.json
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Original file line number Diff line number Diff line change
Expand Up @@ -789,6 +789,61 @@
]
}
},
{
"kind": "value",
"name": "dynsym_entries",
"documentation": "Number of entries in the dynamic symbol table found in the ELF file.",
"type": "i"
},
{
"kind": "array",
"name": "dynsym",
"documentation": "A zero-based array of symbol objects, one for each entry in found in the ELF's DYNSYM. Individual symbol objects can be accessed by using the [] operator.",
"structure":
{
"kind": "struct",
"name": "dynsym",
"documentation": "",
"attributes": [
{
"kind": "value",
"name": "name",
"documentation": "The symbol's name.",
"type": "s"
},
{
"kind": "value",
"name": "value",
"documentation": "A value associated with the symbol. Generally a virtual address.",
"type": "i"
},
{
"kind": "value",
"name": "size",
"documentation": "The symbol's size.",
"type": "i"
},
{
"kind": "value",
"name": "type",
"documentation": "The type of symbol. Built values are: STT_NOTYPE, STT_OBJECT, STT_FUNC, STT_SECTION, STT_FILE, STT_COMMON, STT_TLS.",
"type": "i"
},
{
"kind": "value",
"name": "bind",
"documentation": "The binding of the symbol. Builtin values are: STB_LOCAL, STB_GLOBAL, STB_WEAK.",
"type": "i"
},
{
"kind": "value",
"name": "shndx",
"documentation": "The section index which the symbol is associated with.",
"type": "i"
}
]
}
},
{
"kind": "function",
"name": "symtab_symbol",
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29 changes: 29 additions & 0 deletions tests/cpp/parser_tests.cpp
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Expand Up @@ -7354,5 +7354,34 @@ rule test_rule
EXPECT_EQ(input_text, driver.getParsedFile().getTextFormatted());
}

TEST_F(ParserTests,
ParseELFDynsym) {
prepareInput(
R"(import "elf"

rule test_rule
{
condition:
elf.dynsym_entries == 1 or
elf.dynsym[0].name == "name" or
elf.dynsym[0].value == "value" or
elf.dynsym[0].size == 2 or
elf.dynsym[0].type == elf.STT_NOTYPE or
elf.dynsym[0].type == elf.STT_OBJECT or
elf.dynsym[0].type == elf.STT_FUNC or
elf.dynsym[0].type == elf.STT_SECTION or
elf.dynsym[0].type == elf.STT_FILE or
elf.dynsym[0].type == elf.STT_COMMON or
elf.dynsym[0].type == elf.STT_TLS or
elf.dynsym[0].bind == 3 or
elf.dynsym[0].shndx == 3
}
)");

EXPECT_TRUE(driver.parse(input));
ASSERT_EQ(1u, driver.getParsedFile().getRules().size());

EXPECT_EQ(input_text, driver.getParsedFile().getTextFormatted());
}
}
}
44 changes: 44 additions & 0 deletions tests/python/test_parser.py
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Expand Up @@ -2004,6 +2004,50 @@ def test_parse_pe_signatures_x_algorithm_oid(self):
condition:
pe.signatures[0].algorithm_oid == "1.2.840.113549.1.1.11"
}
'''

self.assertEqual(expected, yara_file.text_formatted)

def test_parse_elf_dynsym(self):
yara_file = yaramod.Yaramod().parse_string(parser_mode=yaramod.ParserMode.Regular, str=r'''import "elf"

rule test_rule {
condition:
elf.dynsym_entries == 1 or
elf.dynsym[0].name == "name" or
elf.dynsym[0].value == "value" or
elf.dynsym[0].size == 2 or
elf.dynsym[0].type == elf.STT_NOTYPE or
elf.dynsym[0].type == elf.STT_OBJECT or
elf.dynsym[0].type == elf.STT_FUNC or
elf.dynsym[0].type == elf.STT_SECTION or
elf.dynsym[0].type == elf.STT_FILE or
elf.dynsym[0].type == elf.STT_COMMON or
elf.dynsym[0].type == elf.STT_TLS or
elf.dynsym[0].bind == 3 or
elf.dynsym[0].shndx == 3
}
''')

expected = r'''import "elf"

rule test_rule
{
condition:
elf.dynsym_entries == 1 or
elf.dynsym[0].name == "name" or
elf.dynsym[0].value == "value" or
elf.dynsym[0].size == 2 or
elf.dynsym[0].type == elf.STT_NOTYPE or
elf.dynsym[0].type == elf.STT_OBJECT or
elf.dynsym[0].type == elf.STT_FUNC or
elf.dynsym[0].type == elf.STT_SECTION or
elf.dynsym[0].type == elf.STT_FILE or
elf.dynsym[0].type == elf.STT_COMMON or
elf.dynsym[0].type == elf.STT_TLS or
elf.dynsym[0].bind == 3 or
elf.dynsym[0].shndx == 3
}
'''

self.assertEqual(expected, yara_file.text_formatted)