yara

package module
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 Go to latest Published: Jun 26, 2023 License: BSD-2-Clause Imports: 10 Imported by: 37

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go-yara

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Go bindings for YARA, staying as close as sensible to the library's C-API while taking inspiration from the yara-python implementation.

Installation

Unix

On a Unix system with libyara, its header files, and pkg-config installed, the following should simply work, provided that GOPATH is set:

go get github.com/hillu/go-yara
go install github.com/hillu/go-yara

The pkg-config program should be able to output the correct compiler and linker flags from the yara.pc file that has been generated and installed by YARA's build system. If libyara has been installed to a custom location, the PKG_CONFIG_PATH environment variable can be used to point pkg-config at the right yara.pc file. If pkg-config cannot be used at all, please refer to the "Build Tags" section.

Linker errors in the compiler output such as

undefined reference to `yr_compiler_add_file'

indicate that the linker is probably looking at an old version of libyara. Please refer to the "Build Tags" section below on how to work with old YARA versions.

Cross-building

go-yara can be cross-built for a different CPU architecture/operating system platform, provided a C cross-compiler for the target platform is available to be used by the cgo tool.

After the yara library has been built from its source tree using the proper C cross-compiler through the usual configure / make / make install steps, go-yara can be built and installed. Some environment variables need to be set when running go build or go install:

  • GOOS, GOARCH indicate the cross compilation target.
  • CGO_ENABLED has to be set to 1 beacuse it defaults to 0 when cross-compiling.
  • CC has to specified because cgo has no prior knowledge about what C compiler to chose for cross-compiling. (it defaults to the system C compiler, usually gcc).
  • PKG_CONFIG_PATH has to be set in so that pkg-config which is run by cgo for determining compiler and linker flags can find the yara.pc file generated while cross-building yara.
Example: Cross-building for Windows on Debian/streach

Install the MinGW C compiler gcc-mingw-w64-i686, gcc-mingw-w64-x86-64 for Win32, Win64, respectively.

Build libyara and go-yara for Win32:

$ cd ${YARA_SRC} \
  && ./bootstrap.sh \
  && ./configure --host=i686-w64-mingw32 --disable-magic --disable-cuckoo --without-crypto --prefix=${YARA_SRC}/i686-w64-mingw32 \
  && make -C ${YARA_SRC} \
  && make -C ${YARA_SRC} install 
$ GOOS=windows GOARCH=amd64 CGO_ENABLED=1 \
  CC=i686-w64-mingw32-gcc \
  PKG_CONFIG_PATH=${YARA_SRC}/i686-w64-mingw32/lib/pkgconfig \
  go inxstall -ldflags '-extldflags "-static"' github.com/hillu/go-yara

Build libyara and go-yara for Win64:

$ cd ${YARA_SRC} \
  && ./bootstrap.sh \
  && ./configure --host=x86_64-w64-mingw32 --disable-magic --disable-cuckoo --without-crypto --prefix=${YARA_SRC}/x86_64-w64-mingw32 \
  && make -C ${YARA_SRC} \
  && make -C ${YARA_SRC} install 
$ GOOS=windows GOARCH=amd64 CGO_ENABLED=1 \
  CC=x86_64-w64-mingw32-gcc \
  PKG_CONFIG_PATH=${YARA_SRC}/x86_64-w64-mingw32/lib/pkgconfig \
  go install -ldflags '-extldflags "-static"' github.com/hillu/go-yara

Build Tags

go-yara is tested with the latest stable version of YARA, currently 3.11. If you need to to build with an older version of YARA, certain features that are not present in older versions can be excluded by passing a build tag such as yara3.7, yara3.6, yara3.5, etc.. You also need to pass the tag when you build your own project.

The build tag yara_static can be used to tell the Go toolchain to run pkg-config with the --static switch. This is not enough for a static build; the appropriate linker flags (e.g. -extldflags "-static") still need to be passed to the go tool.

The build tag no_pkg_config can be used to tell the Go toolchain not to use pkg-config's output. In this case, any compiler or linker flags have to be set via the CGO_CFLAGS and CGO_LDFLAGS environment variables, e.g.:

export CGO_CFLAGS="-I${YARA_SRC}/libyara/include"
export CGO_LDFLAGS="-L${YARA_SRC}/libyara/.libs -lyara"
go install -tags no_pkg_config github.com/hillu/go-yara

License

BSD 2-clause, see LICENSE file in the source distribution.

Author

Hilko Bengen bengen@hilluzination.de

Documentation

Overview

Package yara provides bindings to the YARA library.

Index

Constants

View Source 
const (
	// ScanFlagsFastMode avoids multiple matches of the same string
	// when not necessary.
	ScanFlagsFastMode = C.SCAN_FLAGS_FAST_MODE
	// ScanFlagsProcessMemory causes the scanned data to be
	// interpreted like live, in-prcess memory rather than an on-disk
	// file.
	ScanFlagsProcessMemory = C.SCAN_FLAGS_PROCESS_MEMORY
)

Variables

This section is empty.

Functions

func Finalize added in v1.1.0 

func Finalize() error

Finalize releases all the resources allocated by the YARA library. It should be called by the program when it no longer needs YARA, e.g. just before the program exits. It is not strictly necessary to call Finalize because the allocated memory will be freed on program exit; however, explicitly-freed resources will not show up as a leak in memory profiling tools.

A good practice is calling Finalize as a deferred function in the program's main function: 

defer yara.Finalize()

func GetConfiguration added in v1.1.0 

func GetConfiguration(name ConfigName) (interface{}, error)

GetConfiguration gets a global YARA configuration option.

func SetConfiguration added in v1.1.0 

func SetConfiguration(name ConfigName, src interface{}) error

SetConfiguration sets a global YARA configuration option.

Types

type Compiler 

type Compiler struct {
	Errors   []CompilerMessage
	Warnings []CompilerMessage
	// contains filtered or unexported fields
}

A Compiler encapsulates the YARA compiler that transforms rules into YARA's internal, binary form which in turn is used for scanning files or memory blocks.

func NewCompiler 

func NewCompiler() (*Compiler, error)

NewCompiler creates a YARA compiler.

func (*Compiler) AddFile 

func (c *Compiler) AddFile(file *os.File, namespace string) (err error)

AddFile compiles rules from a file. Rules are added to the specified namespace.

If this function returns an error, the Compiler object will become unusable.

func (*Compiler) AddString 

func (c *Compiler) AddString(rules string, namespace string) (err error)

AddString compiles rules from a string. Rules are added to the specified namespace.

If this function returns an error, the Compiler object will become unusable.

func (*Compiler) DefineVariable 

func (c *Compiler) DefineVariable(identifier string, value interface{}) (err error)

DefineVariable defines a named variable for use by the compiler. Boolean, int64, float64, and string types are supported.

func (*Compiler) Destroy 

func (c *Compiler) Destroy()

Destroy destroys the YARA data structure representing a compiler. Since a Finalizer for the underlying YR_COMPILER structure is automatically set up on creation, it should not be necessary to explicitly call this method.

func (*Compiler) DisableIncludes added in v1.0.5 

func (c *Compiler) DisableIncludes()

DisableIncludes disables all include statements in the compiler. See yr_compiler_set_include_callbacks.

func (*Compiler) GetRules 

func (c *Compiler) GetRules() (*Rules, error)

GetRules returns the compiled ruleset.

func (*Compiler) SetIncludeCallback added in v1.0.5 

func (c *Compiler) SetIncludeCallback(cb CompilerIncludeFunc)

SetIncludeCallback sets up cb as an include callback that is called (through Go glue code) by the YARA compiler for every include statement.

type CompilerIncludeFunc added in v1.0.5 

type CompilerIncludeFunc func(name, filename, namespace string) []byte

CompilerIncludeFunc is the type of the function that can be registered through SetIncludeCallback. It is called for every include statement encountered by the compiler. The argument "name" specifies the rule file to be included, "filename" specifies the name of the rule file where the include statement has been encountered, and "namespace" specifies the rule namespace. The sole return value is a byte slice containing the contents of the included file. A return value of nil signals an error to the YARA compiler.

See also: yr_compiler_set_include_callback in the YARA C API documentation.

type CompilerMessage 

type CompilerMessage struct {
	Filename string
	Line     int
	Text     string
}

A CompilerMessage contains an error or warning message produced while compiling sets of rules using AddString or AddFile.

type ConfigName added in v1.1.0 

type ConfigName uint32
const ConfigMaxMatchData ConfigName = C.YR_CONFIG_MAX_MATCH_DATA
const ConfigMaxStringsPerRule ConfigName = C.YR_CONFIG_MAX_STRINGS_PER_RULE
const ConfigStackSize ConfigName = C.YR_CONFIG_STACK_SIZE

type Error added in v1.3.0 

type Error int

Error encapsulates the C API error codes.

func (Error) Error added in v1.3.0 

func (e Error) Error() string

type Match added in v1.0.6 

type Match struct {
	// contains filtered or unexported fields
}

Match represents a string match.

func (*Match) Base added in v1.3.0 

func (m *Match) Base() int64

Base returns the base offset of the memory block in which the string match occurred.

func (*Match) Data added in v1.0.6 

func (m *Match) Data() []byte

Data returns the blob of data associated with the string match.

func (*Match) Offset added in v1.0.6 

func (m *Match) Offset() int64

Offset returns the offset at which the string match occurred.

type MatchRule 

type MatchRule struct {
	Rule      string
	Namespace string
	Tags      []string
	Meta      map[string]interface{}
	Strings   []MatchString
}

A MatchRule represents a rule successfully matched against a block of data.

type MatchRules added in v1.0.7 

type MatchRules []MatchRule

MatchRules is used to collect matches that are returned by the simple (*Rules).Scan* methods.

func (*MatchRules) RuleMatching added in v1.0.7 

func (mr *MatchRules) RuleMatching(r *Rule) (abort bool, err error)

RuleMatching implements the ScanCallbackMatch interface for MatchRules.

type MatchString 

type MatchString struct {
	Name   string
	Base   uint64
	Offset uint64
	Data   []byte
}

A MatchString represents a string declared and matched in a rule.

type MemoryBlock added in v1.3.0 

type MemoryBlock struct {
	// Base contains the base address of the current block
	Base uint64
	// Size contains the size of the current block
	Size uint64
	// FetchData is used to read size bytes into a byte slice
	FetchData func([]byte)
}

MemoryBlock is returned by the MemoryBlockIterator's First and Next methods

type MemoryBlockIterator added in v1.3.0 

type MemoryBlockIterator interface {
	First() *MemoryBlock
	Next() *MemoryBlock
}

MemoryBlockIterator is a Go representation of YARA's YR_MEMORY_BLOCK_ITERATOR mechanism that is used within yr_rules_mem_scan_blobs.

type Meta added in v1.2.0 

type Meta struct {
	Identifier string
	Value      interface{}
}

Meta represents a rule meta variable. Value can be of type string, int, boolean, or nil.

type Object added in v1.0.7 

type Object struct {
	// contains filtered or unexported fields
}

type Rule added in v1.0.5 

type Rule struct {
	// contains filtered or unexported fields
}

Rule represents a single rule as part of a ruleset.

func (*Rule) Disable added in v1.0.5 

func (r *Rule) Disable()

Disable disables a single rule.

func (*Rule) Enable added in v1.0.5 

func (r *Rule) Enable()

Enable enables a single rule.

func (*Rule) Identifier added in v1.0.5 

func (r *Rule) Identifier() string

Identifier returns the rule's name.

func (*Rule) IsGlobal added in v1.2.0 

func (r *Rule) IsGlobal() bool

IsGlobal returns true if the rule is marked as global.

func (*Rule) IsPrivate added in v1.2.0 

func (r *Rule) IsPrivate() bool

IsPrivate returns true if the rule is marked as private.

func (*Rule) MetaList added in v1.2.0 

func (r *Rule) MetaList() (metas []Meta)

MetaList returns the rule's meta variables as a list of Meta objects. It does not share the limitation of Metas().

func (*Rule) MetaMap added in v1.2.0 

func (r *Rule) MetaMap() (metas map[string][]interface{})

MetaMap returns a map containing the rule's meta variables, with the variable names as keys. Values are collected into lists, this allows for multiple variables with the same; individual values can be of type string, int, bool, or nil.

func (*Rule) Metas deprecated added in v1.0.5 

func (r *Rule) Metas() (metas map[string]interface{})

Metas returns a map containing the rule's meta variables, with the variable names as keys. Values can be of type string, int, bool, or nil.

Deprecated: If there are multiple meta variables with the same name, the returned map contains only the last variable.

Use MetaList or MetaMap instead.

func (*Rule) Namespace added in v1.0.5 

func (r *Rule) Namespace() string

Namespace returns the rule's namespace.

func (*Rule) Strings added in v1.0.6 

func (r *Rule) Strings() (strs []String)

Strings returns the rule's strings.

func (*Rule) Tags added in v1.0.5 

func (r *Rule) Tags() (tags []string)

Tags returns the rule's tags.

type Rules 

type Rules struct {
	// contains filtered or unexported fields
}

Rules contains a compiled YARA ruleset.

func Compile 

func Compile(rules string, variables map[string]interface{}) (r *Rules, err error)

Compile compiles rules and an (optional) set of variables into a Rules object in a single step.

func LoadRules 

func LoadRules(filename string) (*Rules, error)

LoadRules retrieves a compiled ruleset from filename.

func MustCompile 

func MustCompile(rules string, variables map[string]interface{}) (r *Rules)

MustCompile is like Compile but panics if the rules and optional variables can't be compiled. Like regexp.MustCompile, it allows for simple, safe initialization of global or test data.

func ReadRules 

func ReadRules(rd io.Reader) (*Rules, error)

ReadRules retrieves a compiled ruleset from an io.Reader.

func (*Rules) DefineVariable 

func (r *Rules) DefineVariable(identifier string, value interface{}) (err error)

DefineVariable defines a named variable for use by the compiler. Boolean, int64, float64, and string types are supported.

func (*Rules) Destroy 

func (r *Rules) Destroy()

Destroy destroys the YARA data structure representing a ruleset. Since a Finalizer for the underlying YR_RULES structure is automatically set up on creation, it should not be necessary to explicitly call this method.

func (*Rules) GetRules added in v1.0.5 

func (r *Rules) GetRules() (rv []Rule)

GetRules returns a slice of rule objects that are part of the ruleset.

func (*Rules) Save 

func (r *Rules) Save(filename string) (err error)

Save writes a compiled ruleset to filename.

func (*Rules) ScanFile 

func (r *Rules) ScanFile(filename string, flags ScanFlags, timeout time.Duration) (matches []MatchRule, err error)

ScanFile scans a file using the ruleset, returning matches via a list of MatchRule objects.

func (*Rules) ScanFileDescriptor 

func (r *Rules) ScanFileDescriptor(fd uintptr, flags ScanFlags, timeout time.Duration) (matches []MatchRule, err error)

ScanFileDescriptor scans a file using the ruleset, returning matches via a list of MatchRule objects.

func (*Rules) ScanFileDescriptorWithCallback added in v1.0.7 

func (r *Rules) ScanFileDescriptorWithCallback(fd uintptr, flags ScanFlags, timeout time.Duration, cb ScanCallback) (err error)

ScanFileDescriptorWithCallback scans a file using the ruleset. For every event emitted by libyara, the appropriate method on the ScanCallback object is called.

func (*Rules) ScanFileWithCallback added in v1.0.7 

func (r *Rules) ScanFileWithCallback(filename string, flags ScanFlags, timeout time.Duration, cb ScanCallback) (err error)

ScanFileWithCallback scans a file using the ruleset. For every event emitted by libyara, the appropriate method on the ScanCallback object is called.

func (*Rules) ScanMem 

func (r *Rules) ScanMem(buf []byte, flags ScanFlags, timeout time.Duration) (matches []MatchRule, err error)

ScanMem scans an in-memory buffer using the ruleset, returning matches via a list of MatchRule objects.

func (*Rules) ScanMemBlocks added in v1.3.0 

func (r *Rules) ScanMemBlocks(mbi MemoryBlockIterator, flags ScanFlags, timeout time.Duration) (matches []MatchRule, err error)

ScahMemBlocks scans over a MemoryBlockIterator using the ruleset, returning matches via a list of MatchRule objects..

func (*Rules) ScanMemBlocksWithCallback added in v1.3.0 

func (r *Rules) ScanMemBlocksWithCallback(mbi MemoryBlockIterator, flags ScanFlags, timeout time.Duration, cb ScanCallback) (err error)

ScanMemBlocksWithCallback scans over a MemoryBlockIterator using the ruleset. For every event emitted by libyara, the appropriate method on the ScanCallback object is called.

func (*Rules) ScanMemWithCallback added in v1.0.7 

func (r *Rules) ScanMemWithCallback(buf []byte, flags ScanFlags, timeout time.Duration, cb ScanCallback) (err error)

ScanMemWithCallback scans an in-memory buffer using the ruleset. For every event emitted by libyara, the appropriate method on the ScanCallback object is called.

func (*Rules) ScanProc 

func (r *Rules) ScanProc(pid int, flags ScanFlags, timeout time.Duration) (matches []MatchRule, err error)

ScanProc scans a live process using the ruleset, returning matches via a list of MatchRule objects.

func (*Rules) ScanProcWithCallback added in v1.0.7 

func (r *Rules) ScanProcWithCallback(pid int, flags ScanFlags, timeout time.Duration, cb ScanCallback) (err error)

ScanProcWithCallback scans a live process using the ruleset. For every event emitted by libyara, the appropriate method on the ScanCallback object is called.

func (*Rules) Write 

func (r *Rules) Write(wr io.Writer) (err error)

Write writes a compiled ruleset to an io.Writer.

type ScanCallback added in v1.0.7 

type ScanCallback interface{}

ScanCallback is a placeholder for different interfaces that may be implemented by the callback object that is passed to the (*Rules).Scan*WithCallback methods.

type ScanCallbackFinished added in v1.0.7 

type ScanCallbackFinished interface {
	ScanFinished() (bool, error)
}

ScanCallbackFinished is used to signal that a scan has finished. The ScanFinished method corresponds to YARA's CALLBACK_MSG_SCAN_FINISHED message.

type ScanCallbackMatch added in v1.0.7 

type ScanCallbackMatch interface {
	RuleMatching(*Rule) (bool, error)
}

ScanCallbackMatch is used to record rules that matched during a scan. The RuleMatching method corresponds to YARA's CALLBACK_MSG_RULE_MATCHING message.

type ScanCallbackModuleImport added in v1.0.7 

type ScanCallbackModuleImport interface {
	ImportModule(string) ([]byte, bool, error)
}

ScanCallbackModuleImport is used to provide data to a YARA module. The ImportModule method corresponds to YARA's CALLBACK_MSG_IMPORT_MODULE message.

type ScanCallbackModuleImportFinished added in v1.0.7 

type ScanCallbackModuleImportFinished interface {
	ModuleImported(*Object) (bool, error)
}

ScanCallbackModuleImportFinished can be used to free resources that have been used in the ScanCallbackModuleImport implementation. The ModuleImported method corresponds to YARA's CALLBACK_MSG_MODULE_IMPORTED message.

type ScanCallbackNoMatch added in v1.0.7 

type ScanCallbackNoMatch interface {
	RuleNotMatching(*Rule) (bool, error)
}

ScanCallbackNoMatch is used to record rules that did not match during a scan. The RuleNotMatching method corresponds to YARA's CALLBACK_MSG_RULE_NOT_MATCHING mssage.

type ScanFlags 

type ScanFlags int

ScanFlags are used to tweak the behavior of Scan* functions.

type Scanner added in v1.2.0 

type Scanner struct {
	// contains filtered or unexported fields
}

Scanner contains a YARA scanner (YR_SCANNER). The main difference to Rules (YR_RULES) is that it is possible to set variables in a thread-safe manner (cf. https://github.com/VirusTotal/yara/issues/350).

func NewScanner added in v1.2.0 

func NewScanner(r *Rules) (*Scanner, error)

NewScanner creates a YARA scanner.

func (*Scanner) DefineVariable added in v1.2.0 

func (s *Scanner) DefineVariable(identifier string, value interface{}) (err error)

DefineVariable defines a named variable for use by the scanner. Boolean, int64, float64, and string types are supported.

func (*Scanner) Destroy added in v1.2.0 

func (s *Scanner) Destroy()

Destroy destroys the YARA data structure representing a scanner. Since a Finalizer for the underlying YR_SCANNER structure is automatically set up on creation, it should not be necessary to explicitly all this method.

func (*Scanner) GetLastErrorRule added in v1.3.0 

func (s *Scanner) GetLastErrorRule() (r *Rule)

GetLastErrorRule returns the Rule which caused the last error

The result is nil, if scanner returned no rule

func (*Scanner) GetLastErrorString added in v1.3.0 

func (s *Scanner) GetLastErrorString() (r *String)

GetLastErrorString returns the String which caused the last error

The result is nil, if scanner returned no string

func (*Scanner) ScanFile added in v1.2.0 

func (s *Scanner) ScanFile(filename string) (matches []MatchRule, err error)

ScanFile scans a file using the scanner.

If a callback object has been set for the scanner using SetCAllback, matches is nil and the callback object is used instead to collect scan events.

func (*Scanner) ScanFileDescriptor added in v1.2.0 

func (s *Scanner) ScanFileDescriptor(fd uintptr) (matches []MatchRule, err error)

ScanFileDescriptor scans a file using the scanner.

If a callback object has been set for the scanner using SetCAllback, matches is nil and the callback object is used instead to collect scan events.

func (*Scanner) ScanMem added in v1.2.0 

func (s *Scanner) ScanMem(buf []byte) (matches []MatchRule, err error)

ScanMem scans an in-memory buffer using the scanner.

If a callback object has been set for the scanner using SetCAllback, matches is nil and the callback object is used instead to collect scan events.

func (*Scanner) ScanMemBlocks added in v1.3.0 

func (s *Scanner) ScanMemBlocks(mbi MemoryBlockIterator, cb ScanCallback) (matches []MatchRule, err error)

ScahMemBlocks scans over a MemoryBlockIterator using the scanner.

If a callback object has been set for the scanner using SetCAllback, matches is nil and the callback object is used instead to collect scan events.

func (*Scanner) ScanProc added in v1.2.0 

func (s *Scanner) ScanProc(pid int) (matches []MatchRule, err error)

ScanProc scans a live process using the scanner.

If a callback object has been set for the scanner using SetCAllback, matches is nil and the callback object is used instead to collect scan events.

func (*Scanner) SetCallback added in v1.2.0 

func (s *Scanner) SetCallback(cb ScanCallback) *Scanner

SetCallback sets a callback object for the scanner. For every event emitted by libyara during subsequent scan, the appropriate method on the ScanCallback object is called.

For the common case where only a list of matched rules is relevant, setting a callback object is not necessary.

func (*Scanner) SetFlags added in v1.2.0 

func (s *Scanner) SetFlags(flags ScanFlags) *Scanner

SetFlags sets flags for the scanner.

func (*Scanner) SetTimeout added in v1.2.0 

func (s *Scanner) SetTimeout(timeout time.Duration) *Scanner

SetTimeout sets a timeout for the scanner.

type String added in v1.0.6 

type String struct {
	// contains filtered or unexported fields
}

String represents a string as part of a rule.

func (*String) Identifier added in v1.0.6 

func (s *String) Identifier() string

Identifier returns the string's name.

func (*String) Matches added in v1.0.6 

func (s *String) Matches() (matches []Match)

Matches returns all matches that have been recorded for the string.

Source Files

View all Source files

Directories

Path Synopsis
_examples
simple-yara

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