# Basic usage

## Getting headers and sections

readpe is the right tool for parsing PE files without infer anything regarding its fields and values. Using readpe you can see all basic PE file information. For example, in order to see the Optional Header, you could run:

    $ readpe --header optional putty.exe
    Optional/Image header
        Magic number:                    0x10b (PE32)
        Linker major version:            7
        Linker minor version:            10
        Size of .text section:           0x5c000
        Size of .data section:           0x27000
        Size of .bss section:            0
        Entrypoint:                      0x54eb0
        Address of .text section:        0x1000
        Address of .data section:        0x5d000
        ImageBase:                       0x400000
        Alignment of sections:           0x1000
        Alignment factor:                0x1000
        Major version of required OS:    4
        Minor version of required OS:    0
        Major version of image:          0
        Minor version of image:          0
        Major version of subsystem:      4
        Minor version of subsystem:      0
        Size of image:                   0x84000
        Size of headers:                 0x1000
        Checksum:                        0
        Subsystem required:              0x2 (IMAGE_SUBSYSTEM_WINDOWS_GUI)
        DLL characteristics:             0
        DLL characteristics names
        Size of stack to reserve:        0x100000
        Size of stack to commit:         0x1000
        Size of heap space to reserve:   0x100000
        Size of heap space to commit:    0x1000

The Magic Number is 0x10b for PE32 files and 0x20b for PE32+ files.

In order to parse pev tools output you can use the -f / --format option. The following example will output the DOS Header in HTML:

    $ readpe --format html --header dos putty.exe
    <!DOCTYPE html>
    <html lang="en" dir="ltr">
    <head>
        <meta charset="utf-8">
        <title>src/build/readpe --format html --header dos /home/user/PUTTY.EXE</title>
    </head>
    <body>
        <div class="object">
            <h2>DOS Header</h2>
            <p><span class="key"><b>Magic number</b></span>: <span class="value">0x5a4d (MZ)</span></p>
            <p><span class="key"><b>Bytes in last page</b></span>: <span class="value">144</span></p>
            <p><span class="key"><b>Pages in file</b></span>: <span class="value">3</span></p>
            <p><span class="key"><b>Relocations</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>Size of header in paragraphs</b></span>: <span class="value">4</span></p>
            <p><span class="key"><b>Minimum extra paragraphs</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>Maximum extra paragraphs</b></span>: <span class="value">65535</span></p>
            <p><span class="key"><b>Initial (relative) SS value</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>Initial SP value</b></span>: <span class="value">0xb8</span></p>
            <p><span class="key"><b>Initial IP value</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>Initial (relative) CS value</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>Address of relocation table</b></span>: <span class="value">0x40</span></p>
            <p><span class="key"><b>Overlay number</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>OEM identifier</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>OEM information</b></span>: <span class="value">0</span></p>
            <p><span class="key"><b>PE header offset</b></span>: <span class="value">0xf8</span></p>
        </div>
    </body>
    </html>

By combining readpe output with a filter like grep you could easily get the PE file entrypoint in CSV format by filtering the readpe output:

    $ readpe --format csv --header optional putty.exe | grep ^Entry
    Entrypoint,0x4f125

With readpe you can inspect the PE sections as well. Use -S option to see information about all PE sections, just like this:

    $ readpe -S putty.exe
    Sections
        Section
            Name:                            .text
            Virtual Address:                 0x1000
            Physical Address:                0x5bd41
            Size:                            0x5c000 (376832 bytes)
            Pointer To Data:                 0x1000
            Relocations:                     0
            Characteristics:                 0x60000020
            Characteristic Names
                                                 IMAGE_SCN_CNT_CODE
                                                 IMAGE_SCN_MEM_EXECUTE
                                                 IMAGE_SCN_MEM_READ
        Section
            Name:                            .rdata
            Virtual Address:                 0x5d000
            Physical Address:                0x1ceda
            Size:                            0x1d000 (118784 bytes)
            Pointer To Data:                 0x5d000
            Relocations:                     0
            Characteristics:                 0x40000040
            Characteristic Names
                                                 IMAGE_SCN_CNT_INITIALIZED_DATA
                                                 IMAGE_SCN_MEM_READ
        Section
            Name:                            .data
            Virtual Address:                 0x7a000
            Physical Address:                0x5924
            Size:                            0x2000 (8192 bytes)
            Pointer To Data:                 0x7a000
            Relocations:                     0
            Characteristics:                 0xc0000040
            Characteristic Names
                                                 IMAGE_SCN_CNT_INITIALIZED_DATA
                                                 IMAGE_SCN_MEM_READ
                                                 IMAGE_SCN_MEM_WRITE
        Section
            Name:                            .rsrc
            Virtual Address:                 0x80000
            Physical Address:                0x3b90
            Size:                            0x4000 (16384 bytes)
            Pointer To Data:                 0x7c000
            Relocations:                     0
            Characteristics:                 0x40000040
            Characteristic Names
                                                 IMAGE_SCN_CNT_INITIALIZED_DATA
                                                 IMAGE_SCN_MEM_READ

## Looking at function directories

readpe can show you the PE data directories with -d option, like this:

    $ readpe -d putty.exe
    Data directories
        Directory
            IMAGE_DIRECTORY_ENTRY_IMPORT:    0x78378 (240 bytes)
        Directory
            IMAGE_DIRECTORY_ENTRY_RESOURCE:  0x80000 (15248 bytes)
        Directory
            IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG: 0x78318 (72 bytes)
        Directory
            IMAGE_DIRECTORY_ENTRY_IAT:       0x5d000 (1292 bytes)

If the executable has an import directory you may want to see a list of imported functions with -i / --imports option:

    $ readpe -i putty.exe
    Imported functions
        Library
            Name:                            ADVAPI32.dll
            Functions
                Function
                    Name:                            RegCloseKey
                Function
                    Name:                            RegQueryValueExA
                Function
                    Name:                            RegOpenKeyA
                Function
                    Name:                            GetUserNameA
                Function
                    Name:                            EqualSid
                Function
                    Name:                            CopySid
        Library
            Name:                            COMCTL32.dll
            Functions
                Function
                    Ordinal:                         14
                Function
                    Ordinal:                         15
                Function
                    Ordinal:                         17
                Function
                    Ordinal:                         13
        Library
            Name:                            comdlg32.dll
            Functions
                Function
                    Name:                            ChooseColorA
                Function
                    Name:                            ChooseFontA

You can see the exported functions as well by using readpe -e / --exports option.

## Comparing PE pieces

With pehash you can calculate checksums of PE pieces and not only whole PE files. You can for example compare two malwares by similarity using ssdeep. Have a look:

    $ pehash -s CODE ComentarioDeVoz_.cpl
    sections
        section
            section_name:                    CODE
            md5:                             67b498c232dfbe4f5cc0cabc5e78ac42
            sha1:                            32b5df9aaa201bc8cbfed37344aaa77bf842c1d4
            sha256:                          8f5b794da7fdbbc13f1abaae0949b4eb98935c99e7387c7e0dfef5d4f01ea298
            ssdeep:                          6144:2QrIKt9jjmVG0xcpcZTcLexXqS1XGtbNwI/4p3RLjD0OVG:2QrD3mVG0xcpcZTEexvXENv/e3RD0W
    $ pehash -s CODE comentario.cpl
    sections
        section
            section_name:                    CODE
            md5:                             973d11759194c14071aa6963de8f55c7
            sha1:                            1934e0085c8776e3243bf658e95b8943d4f91bc9
            sha256:                          e68349bfcb04b20c11973ce27770570ebb22c8c7750133d073f15f7ec9eeda38
            ssdeep:                          6144:FQrIKt9jjmVG0xcpcZTcLexXqS1XGtbNwI/4p3Zv60G4:FQrD3mVG0xcpcZTEexvXENv/e3J6V

Although the CODE section hashes of each files are different, their ssdeep checksum matches. So, you could probably infer that these are variants.

You can also have the hash for each part using pehash without any option:

    $ pehash -a putty.exe
    file
        filepath:                        /home/user/putty.exe
        md5:                             33c9d1e56152e212367e9c5b01671e45
        sha1:                            9ded3ce2ae09c37ca173bbd3dcb57258b72cdbd5
        sha256:                          b10922648f6ad71f3f20b9acdfacf9aeff706cad6c52737cdc426307ccfa51d9
        ssdeep:                          12288:ApoNd4D7aVwSn8nW+nGQZZcLYX4RXwWLJQ6LU:UoNde7aVT8WvQ3O+4NzLu6w
        imphash:                         dae4485dd029c5e0256f477eda4797a4
    headers
        header
            header_name:                     IMAGE_DOS_HEADER
            md5:                             5084c5d5cfe99932e67450023c068941
            sha1:                            856558429bb575486a46a92ba2684eaab8578cef
            sha256:                          52ea4dd296abe995cc1052a3a29325a8306fc888b3d6fea352d2cebdd83e6eaa
            ssdeep:                          3:WlWUqt/vllPln:idqH
        header
            header_name:                     IMAGE_COFF_HEADER
            md5:                             c29db8cff4c151279ea0f3e1e122bb92
            sha1:                            5df76c71b2fcb937b98d566dad7d353f23f23418
            sha256:                          4dc37a0d8a47d3c713b891a86b92acb28126729da2b7a6a5f3656d23fd8c1a9c
            ssdeep:                          3:OHwkn:wwk
        header
            header_name:                     IMAGE_OPTIONAL_HEADER
            md5:                             0de919344c187babea80d66adc2b0d9e
            sha1:                            4bdec527003b46348d8f9a1594f39f064e9dd680
            sha256:                          97e834e37ee922bca8a9388b2b1663491ddf0d3b20c6d37782aa4f2d1d9ebf64
            ssdeep:                          3:2H2l0lvl9gXH9lhtllrll3lll/ldt1l9tllH:NGlvA3
    sections
        section
            section_name:                    .text
            md5:                             67b498c232dfbe4f5cc0cabc5e78ac42
            sha1:                            32b5df9aaa201bc8cbfed37344aaa77bf842c1d4
            sha256:                          8f5b794da7fdbbc13f1abaae0949b4eb98935c99e7387c7e0dfef5d4f01ea298
            ssdeep:                          6144:6poNd4D7aeaNqZs+iDpnRKnWDX/ZcnGs9BDT7JjZnZZGN+FAFtt6Xa//lrXwW:6poNd4D7aVwSn8nW+nGQZZcLYX4RXwW
        section
            section_name:                    .rdata
            md5:                             6087c2ffc1a7d69f82696a4f2d3aca75
            sha1:                            d69529b6402c520bdbee855c34ce4455112bd1eb
            sha256:                          30b49d20acb96827857ca125ce0d49838fafafe9d7e49523982b2ff1afe54283
            ssdeep:                          3072:mDBKmaes7rlYhoAw/Jt8Lr6hx3bO6ta/4gRul:mS+oAw/Jt836L3bA/
        section
            section_name:                    .data
            md5:                             5578c6fd3e5a0b764a7f2bcde00f9a16
            sha1:                            b71d5142594f56e896e79e12abf729e94512b9e0
            sha256:                          edd88e6b2ccf3dd5624ebd07b8911e2fa51f4ddc7912d4699ed111d28a2a53e5
            ssdeep:                          96:j/1HpvU2Ro26mTfOkf14dBPBgtbAgUhoSkb/:9o26sN2dJ9rIb/
        section
            section_name:                    .rsrc
            md5:                             24b45ea2b1620870730382fb7308a074
            sha1:                            bca5bc464c261f05751c24dce49d70458647e75c
            sha256:                          695707a6f3385838f6e5b58ab45584acb716bec2a2a953327dcb40314f0c0908
            ssdeep:                          192:Icgh8G2PnHGaAnkTjVDBY5disWxDgPWDSL73oqEnngLg:I5SG2vHi4jVDBKjPfL730ng0

The OpenSSL library used by pev supports a wider range of hashing algorithms and you can extend pehash to use them by recompiling its source code.

## Analyzing suspicious files

Suspicious files are nice. We could probably think about lots of suspicious characteristics that PE files may have and all we know is on pescan:

    $ pescan -v Nota.cpl

    file entropy:                    7.986840 (probably packed)
    cpl analysis:                    malware
    fpu anti-disassembly:            no
    imagebase:                       normal - 0x400000
    entrypoint:                      normal - va: 0x15c330 - raw: 0x65530
    DOS stub:                        suspicious - raw: 0x40
    TLS directory:                   not found
    section count:                   3
    .text:                           self-modifying
    .rsrc:                           self-modifying
    .reloc:                          small length
    timestamp:                       normal - Wed, 26 Jun 2013 12:22:16 UTC

pescan is the PE scanner program intended to find any suspicious characteristic on it. It's good for an initial analysis. Further you can analyze things deeply with readpe, pedis, peres and so on.

Strings are also good indicators in general PE file analysis. To avoid the problem with Unicode and ASCII strings, we've developed our own strings dumper for PE files. With pestr you know exactly where the string is inside the file and you don't need to specify whether you are looking for ASCII or Unicode strings. pestr catches both.

    $ pestr --so dotnet.exe
    0x2a69c .text Button4
    0x2a6a9 .text TextBox1
    0x2a6b6 .text 3System.Resources.Tools.StronglyTypedResourceBuilder
    0x2a6eb .text 4.0.0.0
    0x2a6f7 .text KMicrosoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator
    0x2a744 .text 12.0.0.0
    0x2a752 .text My.Settings
    0x2a972 .text _CorExeMain
    0x2a97e .text mscoree.dll
    0x2be7c .rsrc IHDR
    0x2be95 .rsrc pHYs
    0x2beaa .rsrc IDATx
    0x2c1bb .rsrc IEND
    0x2d742 .rsrc VS_VERSION_INFO
    0x2d79e .rsrc VarFileInfo
    0x2d7be .rsrc Translation
    0x2d7e2 .rsrc StringFileInfo

All tools are provided with manpages. Check it out and discover what you can do with pev. ;)